Science. Level 5 B (Houghton Mifflin)

• 11M mat"" ..... I"" in all

a
01 Kilntili< inquiry.

GRADES S4.A. UNDEIISTAHOlNGS "IOUT SOl NTIf lC INQUIRY • D,fll<"" ~""" of """,,,10m ~ eI,fI.. en, ~inK................. "-'1l<1li<_"'_ invoIw '""inti """" InfOlmation; _ iIIYoM ditc<Wl
• C... ,onl OO:!en, ili< knowlO'dgo and undet\landing guIdo KIon1,Ii< irwnti9oot .... and I<.nd"d'IO ....."'. oo:ionlll;. k nowl~ and ~I_ing, • M"""....lia II Impon.on, in.iI 'If>Kts O'KI.n\ 1I1o; inqUiry.

• rted 10 glIM' dlt. In"""'ft a.;,u,Ky and . llows oo:lonll'" 10 Inaly. . . nd quanlify ''''''~. 0 1 in • • I
".ide",",

h..... Iog;..11y ,<)fflillent • kienti'i< • ..pI.nOtion. em~," .'lIu.... nt .. _ "'" oo:"nlll;' pri""pIn, MOdels, _Ih ......... Thl oo:"nt,l;' ,om"",nity a.;,epn _ ....... """ . < ~nOtlons unll! d~O
• klene......"'ft Ihrouyh legitimate "'opIkiIm. _Ing _lion< and CIUftYIng _ oo:ionlied 1>1' ot~ Kilnl"" 1>1' I""';ning .. ideo", •• ,oml*lntI """"'". idonbfying l auity 'e.."..;ng. poim;ng out lIatlmonts u..t 9Obt)cord lhe _ I , _ "'9gftung 1It..-",\i¥e e~ ' iono IOf tho

...... -..Ir_.

,,,,,,It

• klint ,';' Inv.r'"", fOI ",rely. 9'1 .... 011 now ... lIhods co p'orldurrH IOf an In...tigation. or-.op _ 1t<1\ooIo9"'10 Nnp-O¥I 1M
,,,,,,It.

GILlOn W .E. " a IUTlES Of TECHNOLOGICAL OESIGN

• Idenl lfy Ippr~l",e probll .... lor , e
•

~9"

a ..,.MIen Of prod"",.

• Imple .... nl

I

propo>ed dn
• E•• luolllt
0<

prod"" ••

• Com""",;'ot. "'" pr"'ft. of lodmoiog;'11 dnl9n.

The Nature of Science You Can Do What Scientists 00 .... 52 You Can Think like a Scientist .. . . . 54 You Can Be an Inven tor . . .. . .. . . 5 10 You Can Make Decisions ........ 514

Science Safety ................. 516

Meet Dr. Dale Brown Emeagwali. She works as a teacher and researcher at Morgan State University in Baltimore, Maryland. Dr. Emeagwali is a microbiologist, which is a biologist who specializes in studying single-celled organisms, or microorganisms. The goal of her investigations is to gain a better understanding of the processes that take place inside cells. Depending on the question she Is Investigating, Dr. Emeagwali may observe these living things in nature or conduct an experiment in the laboratory.

Scientists ask questions. Then they answer the questions by investigating and e~perimenting. Dr. Emeagwali has asked many questions about how microorganisms ca rry out their life processes, as well as how they affect human health. In one investigation, she demonstrated that a certain che mi cal exists in a type of bacteria called Streptomyces parvu/us. Such discoveries add to the basic knowledge of microb iology. Or. Emeagwali is pleased, though, when her work has practical applications in medicine. In another experiment, she demonstrated that certain molecules co uld be used to stop t he formati on of tumors in people with cancer. Or. Emeagwali understands that for each investigation she carries out she must repeat the procedure many times and get the same results before she ca n conclude that her results are true.

Science investigations involve communicating

with other scientists. In addition to laboratory research, Dr. Emeagwali spends time writirl9 papers about her work in order to communicate with othef scientists. She wants other scientists to be able to repeat her investigations in order to check that her results are valid. Dr. Emeagwali also spends time reading about the work of other scientists to keep infOflTled about the progress others have made in microbiOlogy.

"

Think Like a

Scientist The ways scientists ask and answer questions about the world around them is called scientific inquiry. Scientific inquiry requires certain attitudes, or approaches to thinking about a

problem. To think like a scientist you have to be: • curiouS and ask a lot of questions. • creative and think up new ways to

do things. • able to keep an open mind. That means you c.onsider the ideas of others.

• willing to use measu rement, estimation, and other mathematics skills. • open to changing what you think when

your investigation results surprise you. • willing to question what other people tell you.

What kind of rock is this?

How did this rock form? Where did the different

materials that make up the rock come from?

Use Critical Thinking When you think critically, you make decisions about what others tell you or what you read. Is what you heard on TV or read in a magazine a fact or an opinion? A fact can be checked to make sure it is true. An opinion is what someone thinks about the facts.

Did you ever hear a scientific claim that was hard to believe? When you think, "What evidence is there to

support that claim?" you are thinking critically. You'll also think critically when you evaluate investigation

results. Observations can be interpreted in many ways. You'll judge whether a conclusion is supported by the data collected.

The book states that a sedimentary rod fo rms when roc k frag men ts and other sedi men ts

are pressed and cemented

toge ther= . ......~""

It luuh lik t: frdy"":mb

of different kinds of roc k (ame together to make this roc k. This mus t be a type of sedimentary roc k.

Science Inquiry Applying scientific inquiry helps you understand the world

around you. Suppose you have decided to investigate which color is easiest to see clearly in the dimmest light. Observe In the evening. as daylight fades, you observe the different colored objects around you. As the light becomes dimmer and dimmer, you notice which color remains clear

to your eyes. Ask a Question When you think about what you saw.

heard, or read, you may have questions. HypothHis Think about facts you already know. Do you have an idea about the answer? Write it down. That is your hypothesis.

Experiment Plan a test that will tell if the hypothesis is true or not . list the materials you will need. Write the steps you will follow. Make sure that you keep all conditions the same except the one you are testing. That condition is called the variable. Conclusion Th ink about your results. What do they tell you? Did your results support your hypothesis or show it to be false ? Describe your eJl:periment to others. Communicate your results and conclusion.

My Color Experiment Observe As the light dims, dark colors such as dark blue seem to disappear from sight first. Ask a question I wonder which color can be seen most clearly in the dimmest light? Hypothesis Yellow is the color that can be seen most clearly in the dimmest light.

Experiment I'm going to observe selleral differently colored objects as I dim the light. Then I'm going

to observe which color 1 can see most clearly in the dimmest light. Conclusion The results support my hypothesis. Yellow is the color that can be seen most clearly

in the dimmest light.

Inquiry Process The methods of science may vary from one area of

science to another. Here is a process that some scientists fo llow t o answer questions and make new discoveries.

Make Observations

Ask a Question

Hypothesis

I 00 an Experiment

Draw Condusions

.l Hypothesis is

Supported

Hypoth esis is Not Sup ported

Science Inquiry Skills You'll use many of these skills o f inquiry when you investigate and experiment. • Ask Questions

• Observe • Compare

• Classify • Predict • Measure

• • • • • •

Hypothesize Use Variables Experiment Use Models Communicate Use Numbers

• Record Data • Analyze Dat a

• Infer

• Collaborate • Research

Try It Yourself! Experiment With Energy Beads When you hold Energy Beads in your fist for a while and then

go outdoors and open your hand, the beads change from off·white to many different COIOfS.

o What questions do you have about the Energy Beads? o How would you find out the answers? €) How (ould you use Energy Beads to test a hypothesis?

o Write your plan for an experiment with one variable using Energy Beads. Predict what will happen.

Bean

Inventor Cassandra

wCassie~

Wagner became

an inventor when she was 11 years old.

At that time, she was in middle school. During the summer, she wanted to make

a toy for her pet cat. Cats are attracted to catnip, a plant with a strong odor. Cassie considered including catnip as

part of her toy. When Cassie researched about catnip

on the Internet, she discovered that some people thought an oil in the

plant will repel insects. She could find no proof of that hypothesis, and so she decided to test it herself. In her fi rst experiment, Cassie put a small amount

of the oil from catnip onto a cotton ball. She then observed whether mosquitoes

were repelled by the ball. They were. With the help of a University of Florida professor, Cassie ran further

experiments in a laboratory. She proved that the spray she made with the catnip oil repelled insects just as well as bug sprays sold in stores. Cassie called her bug repellent Bugnip, and she planned to have it produced and sold to consumers. In the future, her efforts may lead to other inventions and better ways of repelling bothersome bugs.

"It was over the summer, and I didn't have much going on. I was just fooling around."

What Is Technology? The tools people make and use, the things they build with tools, and the methods used to accomplish a practical purpose are aU t hnolc,,\ilY. A toy train set is an ex.C1mple of technology. So is a light rail system that

provides transportation in a major city. Scientists use technology, too. For eltClmple, a

telescope makes it possible for scientists to see objects far into space that cannot be seen with just the eyes. Scientists also use measurement technology to make their observations more exact.

Many technologies make the world a better place to live. Sometimes, though, a technology that solves one problem can cause other problems. For example, burning coal in power plants provides power for generators that produce electridty for homes, schools, and industries. However, the burning of coal also can cause acid rain, which can be very harmful t o living things.

A Better Idea ~I

wish I had a better way to . How would you fill in the blank? Everyone wishes he or she could H

do a job more easily or have more fun . Inventors try t o make those wishes come true. Inventing or improving an invention requires time and patience.

A company in Canada had a better idea in 1895. It invented the first power tool. Today. many other tools are powered by electricity-including this cordless power

screwdriver. Today, inventors are still improving power tool technology, including using lasers and microwaves to drill into steel. stone, and glass. Maybe, someday, you will have a better idea for a new power tool.

Coi dlIIl Sa .... ...r

A pc". soudil_ bnI IOC.' ....

letllSC It NIl .. bil." ,.. CM use It .., .....*INW.

How to Be an Inventor

o e o o

Identify a problem. It may be a problem at school. at ho me, o r in your community.

List ways to solve the prol»em. Sometimes the

solution is a new t ool. Other times it may be a new way of doing an old job or activity.

Choose the best solution. Decide which idea you predict will work best. Think about which one you (an carry out. Make a sample. A sample, ca lled a prototype, is th e first t ry. You r idea may need many materials o r none at al l. Choose measuring t ools that w ill help

your design work better.

o

Try out your InvenUon. Use your prototype, o r ask some else t o try it. Keep a record of how it works an d what problems yo u f ind . The more times you try it, the more information you will have.

C) lmprove your invention. Use what you learn ed to

make your design work better. Draw or write about the changes you made and why you made them.

e

Share your in\'entioo. Show your invention to others. Explain how it works. Tell how it makes an activity easier o r more fun. If it did not work as well as yo u wanted, t ell why.

Make

Decisions Trouble for Manatees Manatees are large, slow-moiling marine mammals. An average manatee is about 3 meters long and has a mass of

about 500 kilograms. Manatees are gentle plant eaters. In summer, manatees can be seen along the ocean coasts of Alabama. Georgia, Florida, and South Carolina. In winter,

they migrate to the warm waters of bays and rivers along the Gulf Coast o f Florida. Living near the coast protects the manatees from diseases they might (
with boats. Almost all manatees have scars on their backs from being hit by fast-moving boats.

Deciding What to Do What can be done to protect manatees from harm? Here's how to make you r decision about the

manatees. You can use the same steps to help solve problems in yo ur home, in your school, and in your community.

o LEARN

Learn about the problem. Take the time needed to get the facts. You could talk to an expert, read a science book, or explore a website.

e actions ot her people could take. o DECIDE

LIST Make a list of actions you could take. Add

Think about each action on your list. Identify the risks ill1d benefit s. Decide which

choice is t he best one for you, your school or your community.

o

SHARE Communicate your decision to others.

Science Ii1J

Know the safety rules of your school and classroom

and follow them.

Ii1J Read and follow the safety tips in each Investigate activity.

!i1J

When you plan your own investigations. w rite down how

to keep safe. [i2r Know how to clean up and put away science materials. Keep your work area clean, and tell your teacher about

spills right away. [i2r Know how to safely plug in electrical devices.

Ii!! Wear safety goggles when you r teacher tells you. [i2r Unless your teacher tells you to, never put any science

materials in or near your ears, eyes, or mouth. [i2r Wear gloves when handling live animals. [i2r Wash your hands when your investigation is done.

Caring for Living Things [i2r learn how to care for the plants and animals in your classroom so that they stay healthy and safe. learn how to hold animals carefully.

The life Chapter 1

Cells ...................................................................A2

Chapter 2 Plant Systems ................................................... A46 Chapter 3 Traits of living Things ...................................... A80

Independent Reading

Barbara McClintock

The Amazing Amoeba

Tlirough thl! Cell Wall

Cells perform the most basic functi ons of life. Tiny bacteria and most protists li ve as single cells. Yet large plants and ani mals use trillions of cells to su rvive. Why aren't any single·ce lled organisms as big as you? l ea rning how cells function will help you answer t his question.

LESSON

1

Cells are tiny fluid -filled chambers with parts that never stop moving. Why are cells so important?

Read about them in Lesson 1.

LESSON

2

Some organisms exist as single cells. How do they survive? Read about them in

lesson 2.

LESSON

All living organisms can be grouped into six kingdoms. What are the kingdoms? Read about them in

3

lesson 3. LESSON Blood, muscles, bones, and nerves- are they made of different types of cells? Read about it in lesson 4.

What Are the Parts of a Cell? Why It Matters ... All living things, from water plarlts to hippos, are made of cells. When you learn a bout the pa rts of

celis and thei r functions, you can better understand how organisms like this hippopotamus live and in teract with their environments.

PREPARE TO INVESTIGATE

Inquiry Skill Communicate You can share science results by making

sketches, charts, graphs. or

models. and by speaking and writing.

Materials • II lillQ:'<;Qpe

• prepared slides of various plant and animal tissues

Science ilnd Math Toolbox For step 2, J\"Vi(>W Using a Microscope on page H2.

Get Closer! Procedure

o

Observe Work in a small group. Take turns looking through a microscope at each slide. Note the titles of the slides, which tell the sources of the samples.

e

Communicate Draw a picture of the ce lls in

e

Compare Compare drawings with the

each sample. Next to the picture write the name of the sample, and w hether it comes from a plant or an animal.

other members of your group. Discuss how all the plant cells are similar. Discuss how all the anim al cells ore similar.

<)

Use Models After you d iscuss the cells with your group, draw a diagram of a typical

plant cell and a diagram of a typical animal cell.

Conclusion 1.

Communicate Discuss how your diagrams of typical cells show the differences between

plant and animal cells.

2.

Infer Compare the outer boundaries of an animal cell and a plant cell. What d ifferences between plants and animals do the cell boundaries help explain?

3.

Hypothesize 00 you think the cells of all plants and animals sh are the characteristics you ident ified? How could you t est your hypothesis?

I

Use Models Cells vary a

I great deal in size. You r cells are almost 100 times bigger than a bacteria cell. Build or draw a model to show the difference in size between a human and a bacteria cell.

v

at1l by

Reading

VOCABULARY

MAIN IDEA Cells a re t he

.M

(ell

." ."

nucleus orga nelle

Cells

READING SKill Compare an d Contrast Use a Venn diagram to list similarities and differences betwEen animal cells and plant cells.

'X)

Year 1665 ~ Hooke used a microscope to study thin slices of cork. He observed thin, boxy sections that he called cells .

• Lenon 1

ba~it

un it s of living thing s.

Mit,os(oJ>es allow sde lli ists to le ... n about the p" rts and funct ion s of celis.

Building Blocks of life The basic unit that makes up living things is the cell. All living things, from tiny bacteria to the lnrgest whale, MC made of cells. When you look al mOSlliving things, you (annol see indivictunl cells. Thill is because most cells are much too small to be seen with the unaided eye. The invention of the microscope made it possible for scientists to discover cells and the structures within them. In 1665, English scientist Robert Hooke studied a slice of cork under a microscope. He observed that cork was divided into many tiny, box-shaped sections. Hooke called these se<:tions cells be
.... Today Scientists know that all living things are made of cells. This image from an electron microscope shows a nerve cell nucleus magnified 3,980 times (3,980X).

The (ell Theory By using new and improved

microscopes, scientists were able to Ob<;f>TVe cPlls in mOTt> detail_ In IRIS, Germlln scie ntist Matthias Schleiden compared different plants (lnd plant parts. He concluded that all plants are made of cells. Another scien tist drew the same conclusion about animals. Twen ty years lale r, German physician Rudolf Vircllow reasoned that cells come only from other cells. These conclusions were eventually organized into a single theory known as the celliheory. The theory states: • AI! living things are made of one or more cells. • The cell is the smallest unit of it living organism. • Cells come from other cells. Today, scientists continue to use new equipment and techniques to s tudy cells. The additional evidence con tinues to support the cell theory.

Microscope Development The earliest microscopes used a single lens to collect and focus light. In ti m p_ two Ipn<;f'~ ",prp comhin...-l to fonn a compound ligh t microscope. Its magnifying power is the power of each lens multiplied together. Modem light microscopes can magnify obje<:ts up to 2,000 times, or 2,OOOX. That's powerful enough to sec not just cells, bu t structures wi thin cells. The electron microscope (EM) came into use during the 1930s. EMs use rapidly moving ehxtrons instead of light to make images of objects. EMs may magnify objects 4O,OOOX or mOTe. Today, the scanning electron microscope (SEM) has taken this technology still further. SEMs allow scientists to study the three- dimensional structure of the surfaces of cells and other tiny things. ~ COMPARE AND CONTRAST

How does Hooke·s microscope compare to microscopes today7

A7

Plant Cell A large vacuole and thick cell wall provide shape and structure .

• ndopla,mic foticulum

The Parts of a Cen Cells contain even smaller structures called organelles. These structures perform specific functions in the cell. Animal cells and plant cells have many of the sa me orga nelles, but some are qui te different. As you read through this section, refer to the organelle or cell part in the illustrations. Nudeui The nucl eus directs the activities of the cell. 11 stores a mole<:ule called DNA, which de termines an organism's traits. DNA stores genetic information, which is passed from parents to their offspring. • Lesson 1

9019; appafatus

(ell Membrane The cell membrane is a thin, flexible covering that surrounds all types of cells. 11 allows food, waler, and gases to enter the cell and wastes to leave. (ell Wall In plan t cells only, the cell wall is a rigid outer layer that surround s the cell membrane. The cell wall prote<:ts the cell and helps the plant stand upright. Pores in the cell wall allow ma terials to pass in and out. (ytoplaim Between the nucleus and the cell membrane is the cytoplasm. All of the remain ing organelles are located within the cytopl
Animal Cell

o

A nucleus and several organelles are surrounded by II cell membrane .

cylopl.sm

••

• ,..,,',....,,.,","1"", _-=,:-\-_ •

" Ribosomes Tiny ribosomes arc scattered throughout the cell. Unli ke most other organelles, ribosomes are not surrounded by membranes. Ribosomes assemble compounds called proteins. Proteins milke up the structural components of celis, and

they allow the cell to perform nearly all chemical reactions.

Lysosomes Lysosomes are small, ballshaped organelles that help the cell break down nutrients and old cell parts. Lysosomes are common in animal cells, but rare in plants. Vacuoles Vacuoles are membranebound 5.1CS th(lt arc filled with fluid. They store water, food, waste, and o ther subs tan ces the cell processes.

Animill cells may have small vacuoles. Plant cells, however, often have onc large, central vacuole. When the vacuole in a plant cell is full, the cell is rigid. If the vacuoles in many cells lose water, the plant will wilt.

Goigi apparatus The Golgi apparatus receil'es proteins, then processes them for "shipment" outside the cell. This organelle is a system of membranes. It modifies and refines proteins, sometimes adding compounds that will protect them from being broken apa rt.

D COMPARE ANDCONTRlST

Describe diffe rences between plant ce ll s and ani mal cells. A9

Chloroplasts Found only in plants and some protists, chloroplasts contain pigments tha t absorb sunlight. They use the energy to mnke food-.l unique process nmong the organelles! The pigment chlorophyll gives plnn ts their gK"Cn color. Mitochondria L..lrge, pennut-shnped organelles, called mitochondria, are known as the "power plnnts" of the cell. Inside them, sugars break apart as they react with oxygen. The process releases carbon dioxide, water, and a lot of energy In both plant and animal cells, the number of mitochondria depends on the amount of energy the cell needs. For example, a muscle cell requires a great deal of energy, and so it has a large number of mitochondria. Endoplasmi( reti(ulum The endoplasmic reticulum (ER) is a sys tem of membranes and tubes. The membrant>s twist and turn through the cell, creating passages through which materials can pass. A cell usu ally contains two kinds of ER, called rough and smooth. Rough ER is dotted with ribosomes. This type of ER is common in cells that secrete lots of proteins. Smooth ER is not covered by ribosomcs. lis activi ties include breaking down toxic substanccs and cont rolling the levels of certain chemicals. ~ (OMPARE AND (ONTRAST

How is smooth

ER different from rough ER?

Review

o MAIN IDEA What are the three main points of the cell theory?

Cells were first discovered more than 300 years ago.

e VOCABULARY Wr ite a sentence using the terms cell and nucleus. Explain the role of the nucleus in the cell.

e READING SKilL: Compare Microscopes allow sdentisu to look at and study cells.

and Contrast How are the uses of a light micros
o CRITICAL THINKING: Cells contain smaller structures called organelles. Each performs a sped fic IUlKtion. Unli ke animal cells. plant cells are SUIlounded by cell walls. They typically have a boxy shape.

Evaluate How would you determine whether a (ell (arne Irom an animal or a plant? Discuss cell pans in your answer.

o INQUIRY SKill: Communicate Write a paragraph explaining how a cell membrane is similar to a cell wall? How is it different?

..t TEST PREP Which of these organelles is pan of a plant cell but not an animal cell? A. mitochondria B. cell membrane

MATH

Make a Table A picture from a microscope has a width of 8 em. The power of the microscope is l00X. What is the width of the specimen that the pkture shom?

TECHNOLOGY

Make a Diagram Research the history and design of the light microscope, the electron microscope, and the S(anning electron mkroscope. Choose one and create a diagram to show how it works.

C. chloroplast D. nudeus ~ Technology . . Visit www.eduplace.(omlscpltofilld out more about tile parlS of a cell.

Al1

How Do S e Organisms Live? Why It Matters... Single-celled organisms like this dinoflagellate produce much of the food and oxygen that sustain life on Earth. Other single-celled organisms are a major cause of disease.

PREPARE TO INVESTIGATE

Inquiry Skill HypotheSize When ~ou

hypothesize, you suggest a reason for what you have observed and describe how you will test your reasoning.

Materials • llled)ur;ny wp

• warm water

• cup Of bowl • teaspoon

• ~gar • packet of yeast • 2 SNlable plastic bags • cafeteria tray • paper tOW('ls • lamp

Science and Math Toolbox For step 1, review Making It Chart to Organize Data on page H11 .

Watch Yeast Feast! Procedure

o e

Y~... t • Water .. Vout+

Om.

5u ar

Water

Collaborate Work in a small group. In your Science Notebook, make a chart like the

one shown. Experiment Pour 3/4 cup of warm water (not hot) into
teaspoons (tsp.) of sugar and 1 tsp. of yeast. Pour the mixture into a sealable plastic bag.

e o o

Squeeze out as much air as you can. Seal the bag completely. Rinse out the bowl. Experiment Repeat Step 2 using a second bag. but this time do not include sugar. Experiment Place both sealed bags on a tray lined with a paper towel. Set the tray on a shelf or tabletop under
Record Data Check the bags at regular intervals over the next day. Record what you observe. Use either words or pictures

to describe what you see.

Conclusion 1.

Compare Describe how the contents of the two bags changed over time. Note important differences in the bags that you observed.

2.

Hypothesize What do you think might have caused the effects you observed? Propose a hypothesis. Describe how you could test this hypothesis.

3.

Compare Share your hypothesis with the class. Compare it with those of other students.

Design an Experiment Do yeast grow better in W
v afn by Reading VOCABULARY

Single-Celled Organisms

(ilia

p.
diffusion flag<1lh,m

p. A.11

MAIN IDEA In single-celled organisms. all life processes

p. <1.11

are carried out in just one cell.

osmosis

p.A17

READING SKILL

life as a Single Cell

Oraw Conclusions Use a (hart like the one shown to organize information about how single-<elled organisms move. Then use the (harlto draw (onclusions.

All living things have the S<1lTIC basic needs. They need to take in food nnd get rid of wastes. They need 10 digest nutrients so Ihcy ca n use

and store energy. They also need to grow and reproduce. Single-celled organisms carry out all of their li fe processes within onc cell. Mos! single-cclled organisms can be seen only with thc aid of a microscope. For this reason,

they are also known as microorganisms. Silcleria, amoebas, and paramecia are examples. The pho tograph below shows a diatom, which also is made of one celL The cell is housed inside a shell thai il ma kes. Dia toms are classified as p rotists, a large and diverse group. Diatoms are an important food source for fish, whales, and other orgllnisms that live in w ilter. When diatoms die, their shells do not brea k d o wn. Instelld, they even tUll11y fo rm a soft, chal ky .~~......",:m aterial. Deposits of th is material are found ~ all over the world. They arc used as insulilting products, cleaning p roduc ts, a nd e xplosives. Much of Earth's petroleum Cllme from di iltoms .

... Diatoms Diatoms live in fresh and salty water. Their shells afe made 01 siliu, which is like glass. Some diatoms may live togethef in a group called a colony.

Interactions With Larger Organisms Single-celled organisms are all around you! Someti mes their effects are helpful. while at ot her times they are harmful. Bacteria, for exa m ple, do the important job of brea king down the remains of dead plants and animals. They return materials from dead organisms back to the environment, where new organisms can use them. Bacteria also help produce and process some foods. Bacteria are used to produce yogurt, sour cream, and buttermilk, as well as cottage cheese, sauerkraut, and pickles. Did you know tha t helpful bac teria live inside you? In fact, your body needs cer tain bitl:tcri" to Jigest food p roperly ""0 to make vitamins. Bacteria can also be harm ful. Strep throat, Lyme disease, and tuberculosis are just a few diseases that come from different bacterial infections. Other bacteria cause disease by producing poisons called toxins.

... Harmful Bacteria These streptococ(i can cause illnesses such as wep throa t.

... Beneficial Bacteria Lactobacilli help make yogurt and cheese.

Antibiotics are drugs that treat b.>.:", .. i,ll infe.:liolls. They jnted",r",

with the life processes of the bacteria while not hanning hum an cells. Many algae are also single-celled organisms. Like plants cells, algae can make their own food using energy from the Sun. [n the process, they give off oxygen. Much of the oxygen in the air comes from algae in the oceans. Algae are also a food source for many ocean animals. Yeasts are another type of singlecelled organism. Yeasts are used to ma ke bread, vinegar, and ethanol. an important gasoline additive. Of the roughly 600 different types of yeasts, a few cause diseases in plan ts, animals, and humans.

~ DRAW CONCLUSIONS Why are bacteria important for all living t hings?

... An amoeba takes in food by SUHounding it with a membrane ~c..

Getting Food All organisms need energy. Some, like plants, make their ow n food. Others take in or eal food from Ihe oulside. Single-cclled organisms get food in different ways. For exam ple, an /lmocb /l ~tretche5 il~ mcmbrnne into arms that surround a food particle. As il closes in, the membrane forms a sac, or vacuole, around the food. Food is digested in the vacuole, then absorbed into the cytoplasm. Und igested food particles are mo\'ed to the cell membraroc. These wastes are washed awa y as the amoeba moves through the water.

1 • lessoo 2

A p.'1ramecium gets food \'ery differently. Its body has a fu nnel called an oral groove. Small hairs called cilia surround the openi ng to the groove. The cilia move bac k and forth , sweeping food parti cles inside. At the bottom of the oral groove, a membrane expands to form a vacuo le around the food. When the vacuole breaks off, food is carried throughout the cell. After it deli\'ers food, the vacuole collects waste products. It then returns to the cell membrane and releases Ihe wasles outside the cell. The cilia of a paramecium sweep food par1icles toward the oral groove on tilt outer surf",e of tilt cell. •

orat

Diffusion Some materials move directly through the organism's cell membrane. One way this occurs is by diffusion. Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. This means that particles travel from areas where they are crowded to areas where they are less crowded. One of the most important substances that passes through the cell membrane is water. Diffusion in which water passes through the cell membrane is called osmosis. Sometimes, osmosis alone is not enough to control the flow of water into or out of a ceiL If too much water flows into II cell, the cell wil] swell This can damage or kill the cell. As a result, some single-<:elled organisms also use vacuoles to remove excess water. In an amoeba, large vacuoles release water through the cell membrane. In a paramecium, small channels direct excess water into a contractile vacuole. When the vacuole is full, it pumps water out the cell membrane. Diffusion and osmosis help explain why cells have such small sizes. To stay alive, cells need food, gases, and other materials that diffuse through the cell membrane. Yet beyond a certain cell size, diffusion could not take place fast enough. The area of the cell membrane would be too small to supply the cell's larger volume.

.. Most euglena are green, singlecelled organisms that live in ponds. They swim by spinnin\l their lon\l whip·like structures, called fla\lella.

Movement Some single-<:elled organisms are able to move from place to place, much like anim .. ls do. Movement enables an organism to find food and shelter, or to escape preda tors. The amoeba moves by pushing its membrane forward. This creates a pseudopod, or "false foot." The paramecium moves by using cilia. The cilia beat back and forth like oars on a boat. Another single-<:elled organism, the euglena, has a long structure that acts like a whip. The structure is c.. l1ed a flagell um. It spins like the propeller of a boat.

~ DRAW (ONClUSIONS ~nd p~r~meciil

Why do am oe b~ ~ need moving part~?

Binary Fission Bacteria reproduce through fission .

--

• Gene tic Information

P;uent Ct ll

Cell Oivides

Copied

Two Identical Ct lls

Reproduction

Budding is another form of reproduction, In budding, a small knob, or bud, fonns on the parent cell. The bud contains the same genetic informa tion as the parent Ct'11. When the bud grows to the size of the parent cell, it breaks off. The new cell is iden tical to the parent. Many yeast cells reproduce through budding. Binary fission and budding are forms of asexual reproduction. Only one parent is involved in this type of reprod uction. The offspring of asexua l reprod uction are iden tical to the parent. Some single-celled organisms can also reprod uce through sexual reprod uction, Two parent cells are involved in this type of reproduction. The offspring have a combination of traits from both pa rents. Dependi ng on thei r environmen t, yeas t and algae switch between these types of reproduction.

Organisms must produce more of thei r kind if the sp«ies is to survive. The process is called reproduction. Single-celled organisms reproduCt' in di fferent ways. One very simple type of reproduction is called binary fission. A bacterial cell reprod uces in this way. Recall tha t a cell contains genetic information tha t is transferred from one generation to the nex t. Before it divides, the parent cell makes a copy of its genetic information. Once the cell grows longer and its genetic information is copied, the Ct'll pinches in the middle. The two sections break apart to form two new cells. The genetic information in each cell is the s,lme so both cells will ha\'e the same exact traits.

~ DRAW CONClUSIDNS

How do yeast and

baderia reproduce 7


• Lenon 2

Budding

Yeast is just one of the single·celled organisms that reproduce by fOl ming buds and blanches .

Review

o MAIN IDEA Which neWs do Bao:;te';a a,~ s;ngl ~· celled O'9"nisms. Thev can be ha' mful 0' benefidal.

single·celled organisms have in common with on:;anisms that have more than ooe cell?

o VOCABULARY Write a senle!lce or shon paragraph using the terms diffusion and osmosis.

To stay alive. single· celled or9"nisms tak e in food and other materials. Many move from plao:;e 10 plao:;e,

f) READING SKILL.: Draw

Some single·celled organisms reproduce th,ough binary fission. and others reproduce th,ough budding.

o CRITICAL THINKING: Apply

Conclusions Suppose you discover a microbe that has bom cil ia and a flagellum. What mighl you conclude about the purpose of the cilia? What might happen if you take a medicine that is strong enough to kill almost all of me bacteria in your body?

o INQUIRY SKILL: Hypothesize Do yeast need air to grow? Propose a hypothesis to answer this question. Describe an experiment to test it.

MATH Make a Graph Suppose you have one amoeba tha t reproduces every hour. as do all its offspring. Draw a graph to show the population growth over five hours. Assume that no amoebas die. Do you think such growth could continue withou t end?

. t TEST PREP Single·celled organisms use flage lla, cilia, or pseudopods to A. move from place to place. B. break down

WRITING

Expository Research a harmful or beneficial bacteria species. such as one described in th is lesson. Write a repan about the effects of the species on people's lives. Do the bacteria affect your life111 so. how1

food.

C. reproduce. D. pump out water.

/-t

'iii.

Technology Visit www.eduplacuomlscpl to find out mor~ about !oiogl... {~ l ed a
History of Science

Louis Pasteur What causes food to spoil? Two hundred years ago, people believed that tiny living arose from the food. This id(,11 was called spontanoous gener,ltion. [\ meant that life could assemble itself from nonliving paris. French scientist Louis Pasteur (1822-1899) argued thill microorganisms came only from their own kind, just as larger organisms do. He proved the case against spontaneous generation with the experiment shown to the right. How Gin spoilage be stopped? Pasteur found that

heating beverages kills or slows the tiny creatures inside them, II process now called pasteurization in his honor. Pasteur also identified b.1cteria and viruses that (;'lIS(' human diseases, and suggested ways to prev('nt infections. In Pas teu r 's time, the typict11 surgeon might not even wash his hands!

W-~

SOCIAL STUDIES

... Pasteur's experiment shows that the bacteria that tlouded the broth must have (orne from the air, not the broth iuelf.

o h~t eu. p.epa.~

two sealed flfils, eacll holding dear broth. He boiled the broth to kill bacteria In diem.

• At a pasteurization plant, milk Is heated in large vats. The temperature is high enough to kill bacteria, but not too high to damage the milk.

o

Afte. a lew day5. die brotll remains de¥ in both fla~ks. Pasteur bruks the seal 01 one fla~k.

Pasteurization helps prated milk from bacteria.

•

Sharing Ideas t

o

Days later. tile broth in the ~ealed remain~ clear. The broth In the unseal~ flasJc be
flask

READING
2. WRITE ... BOUTIT Describe pasteurization. 1 TAlX ABOUT IT Compare physicians" approathes to cleanliness in Pasteur's time and today.

How Do the Cells of Organisms Compare? Why It Matters ...

PREPARE TO INVESTIGATE

Inquiry Skill

By comparing organisms,

scientists learn more about th em.

Comparing and classifying organisms also helps scientists understand and make accurate predictions about

newly·discovered life forms.

Classify Whe n you classify, you group object s by their

cha racteristics.

Materials • index cards • colored pencils or markers

Stience and Math Toolbox For step 1, review Making a Chart

to Organize Data on page H1t.

~ , -

•

Sort What You See Procedure

o e e

Collaborate Work in a small group. In your Science Notebook, list 15 different living

organisms. Use Models Write the name of each

organism on a separate index card. Include a drawing o r photo of the o rgan ism on the card.

Classify Group the index cards according to common characteristics of the organisms. Name and describe each group.

Flowa'

Conclusion 1.

Analyze Data With your group, create a

chart or diagram that shows your classification scheme.

2.

Compare Share your classifications with another group. How is their classification

scheme different from yours?

3.

Classify Work with your group and reclassify

the living organisms. Chose a different characteristic to classify them by.

Inve'Stigate More! Research Use the Internet or books at the library to research other organisms. perhaps some you have

never seen before. How do these organisms fit into your classification s
v

at1l by

Reading

Classifying Living

VOCABULARY fungi kingdom protist

p. "'26

p.1I.24 p.1I25

READING SKill Classify Use a (hart to organize am:! classify

information about organism~

MAIN IDEA Scientists class ify living things by comparing and con lfasting ttleir physical characteriSlics.

Six Kingdoms YOll probably sort your clothes into separate groups. Perhaps you put socks in one drawer and shirts in another. You might also sort books, magaZines, or COS. The process of sorting things by how Ihey are alike and how they arc different is known as classifica tion. Scientists usc a system of classification to sort living things. Originally, people sorted li ving things into two groups-plants and animals. The diffe rences between the two groups seemed dear. Animals could move around. whereas plants could not. The two grou ps reproduced in different ways and usually looked quite different from each other. Once the microscope was invented, however, classification became more complicated. As scien tists quickly discovered, many tiny org.:misms had some traits of plants and some traits of animals. Their cells did not eX.:lctly match either of the cells you explored in Lesson 1. Today, most scientists recognize six ki ngdoms of living things. A kingdom is a large group into which organisms are organized according to their trai ts. Th ree of the six kingd oms are made up mostly of organisms that are microscopic!

... tn th is picture, you can see organisms from the animal (squiHet), plant (moss), and fungi (mushlOom) kingdoms. You can' t see the protiUs or the bacteria, but they're there!

Od, ... dwI,Khristics Bacteria (two

sing1e..:elled

• live alooe or in coiooies • cannot move independently • lack 11 nucleus

mostly Ilngle..:elled

• live ~Iooe or in coiooies • some ca n move independently.

kingdoo)

Prot ists

-~,

• some rIlOSt find lood. some lni'lke food mostly multi..:elled

• live alooe or in coiooies • do not move nJependently • decaying Ini'Itter or living

multi-celled

• speci~li;red cell!; • do not move from plao;e to plao;e • produce lood using sunlight

multi-celled

• specialired cell!; organired into complex systems • can ,no ... independently • feed on all other kingdoms

Fungi

Pla nt

Animal.

Bacteria

Protists

Earth is home 10 a huge number of bacteria. The cells of b.lc teria are described as pro karyotic. This means that they do not con tain a nucleus or organelles surrounded by membranes. There are two bacteria kingdoms: eubacteria and archaebacteria. Most of the bacteria Ihat affect you are eubac teria. Archaebacteria are usually found in harsh environmen ts, such as hot ven ts along the ocean floor. Sollty lakes, and hot springs.

Most pro ti sts are microscopic, singl~llcd organisms. Unlike bacteria, however, protist cells are eu karyotic. This means they have a nucleus and membrane-bound organelles. The cells of a fell' prolists have a cell wal L Some protis ts can make their own food. The protis t kingdom includes protozoa (such as amoebas and paramecia), most types of algae (induding diatoms and seaweed), and slime molds. Prolists may be the most diverse kingdom. D

UASSIFY

How are bacteria a nd prot ists alike? How are they d ille rent?

Spores are pro tu ted by thf (ap until they drop Or Ire bloW!! away.

Gillt _ ---.J The gills produce

The

'''''~

,

mushroom sl;tlk

holds the ~p up so the, wind ~n (atch ani! carry thf spores.

Fungi Most organisms in the fungi kingdom are multicellular, which means they consist of more than one cell. Fungi absorb food , and they help break down dead plnnt nnd animal mntler, Their cells hnl'e orgnneJ1es (lnd a nucleus, which mnkes them eukaryotic cells. Like pl(lnt cells, they also h(l\'e cell walls, but they do not ha\'e chloroplasts. Fungi range in size from microscopic yeast to I(lrger varie ties. You might see shelf fungi on tT('e branches. Fungi indude yellsts, molds, mildews, rusts, and mushrooms. 1 • lesson 3

Some fungi are harmful. They ca use disease and spoil food. Other fungi are used as foods or to make foods and medicines. Fungi do an important job in nature by breaking down once-li\'ing matter. In this way, fungi recycle ma terials and enrich the soil. Mushrooms develop from tiny spores that aT(' small enough to be spread by the wind. The spores become buried under leavcs or soil. There they grow into long, brnnching structures called fil aments. As the filamenls gnlher nutrients from the soil, a button appcMs above the ground. This bu tton grows into a full mushroom with a stalk (lnd 11 ca p at the top. The smooth top of the ca p protects the gills underneath. The gills release spores when the mushroom is full grown. The wind blows the spores ilwny and the process begins all over again.

T Some musllrooms..lih this Illorel, afe edible. Others (onlain deadly toxins. Only an upert should pi(k wild mushroollls!

'" Mosses are among the simples t and smallest plants. They live in moist places,. usually down along the ground.

Plants Plants are complex, multicellular organisms. They vary in size from the tiniest mosses to the tallest trees. As you learned earlier, plant cells contain a nucleus and organelles. This makes plant cells eukaryotic cells. The charilCteristic that almost all plants hal'e in common is the abilit)' to use sunligh t to make food. This process ts called phOiosynthests. In th is process, organelles called chloroplasts absorb energy from su nlight. Plants use that energy to convert carbon dioxide and wa\(>r into sugar and oxygen. Plants, and the animals that eat them, use the energy stored in the sugar to carry out their life processes. So, when you eat plants, you are gaining energy that was stored during photosynthesis. In addition, all animals depend on the oxygen that plants produce in order to survive. When you breathe, you take in oxygen and release clITbon d ioxide. Plants take in the carbon dioxide you release and produce more oxygen that you need. Plants aTe an essential part of this cycle.

In addition to containing chloroplasts, plant cells hal'e other characteristics that make them different from organisms in other kingdoms. Recall that plant cells have a cell wall and a large, central vacuole. These structures provide strength and support, and they allow plants to grow much taller than protists or fungi. What are three UnKlures ",, ~" be fotlnd in plant cells?

'" Baobab trees can live for several thousand years. These 1iY1! on the island of Madagascar.

Animals Look in the mi rror and you will see an organism from the animal kingdom. It's you! Animals range in size from almost microscopic insects to gig~n ti c whales. Ani mals are complex, multicellular organisms. Most animals can move independently, at least at some point in their lives. All respond to stimuli, such as touch or the smell of food. Unlike plan ts, animals cannot make their own food, because their cells lack chloroplasts. Animals get food by eating other organisms. Scientists divide the animal kingdom into smaller groups in many different ways. One way is by separating anim;lls that have in ternal skeletons from animals that do not. Animals Ihal do nOI have Internal skeletons or a backbone are called inverteb rates. They include insects, clams, worms, snails, and crabs. To support their bodies, invertebrates have strong muscles or thick outer coverings.

• Internal skeletons allow vertebrates to support targer, more (omple~ internal organs.

Animals that have internal skeletons and backbones are called vcrtebra h.'s. They Include fish, frogs, snakes, birds, and horses. Humans arc vertebr~tes as well. An internal skeleton gives support to an animal and protects its inlemal organs. Vertebrates are the largest animals. They are not, however, the most numerous. Most animals are invertebrates. In fact, abou t 99 oul of every 100 ani mals are invertebrates. Why do you think Ihis is so?

~m«i!ii

In whllt ways are invertebralM and ~Iebrllies lIlih lind differlMt?

<01 Invertebrates. such as this sea

slug. do not have ~ backbone or an intemal skeleton.

Review

o MAIN IDEA Wha t are the six

Visual Summary

kingdoms into which living things ale classified?

o VOCABULARY Define the tellll

Kingdoms of life

kingdom. Describe how scientists

\ p'obryoles (bacteria)

/

use kingdoms to classify living things.

~ryot es

€) READING SKILL: Classify How do fungi cells differ from

"-

... ba,t.,ia

ba
plant cells? How are they alike?

o CRITICAL THINKING: Apply

/'

.1

"tim

.1

BB

.r.irn.als

/

in..,l1ebfates

List two ways in which animals and plants differ from one another. Re late these differences to the cells of plants and animals.

I

( _ttbr.te,

)

o INQUIRY SKILL: Classify Explain why scientists use celi stlL'cture to classify living things.

.,e TEST PREP Which kingdom is made mostly of single·celled eukaryote'!? A. eubacteria

ART

(reate a Poster Research one venebrate group such as amphibians, fish, reptiles, birds, or mammals. Make a poster that shows the unique characteristics 01 the group,

WRITING

Poetry Wlite a poem about one of the kingdoms of living things. Include facts about the kingdom in the poem.

B. archaebacteria

C. protists D. fungi ~ Technology , . VISit www.eduplace.comlS( pi to fifld 001 more about clas,,;!yiflg or~nis~,

How Are Cells Organized? Why It Matters ... How are you able to digest food, or move from place to place? How are you able to catch a baseball, or dance in t ime to music, or solve a math problem? In humans and other mult icellular organisms. cell organization makes all the processes of life happen.

PREPARE TO INVESTIGATE

Inquiry Skill Ask Questions Scientists ask questions about organisms,

objects, and events. Science inquiry helps test t he answe rs.

Materials • mlCros
• prepared slides of various an imlll

tissues

Science and Math Toolbox For step 2, J!!'Vi!!W Using a Microscope on page H2.

Exploring Tissues Procedure

o e e

Collaborate Work in a small group. In your Science Notebook, draw a chart !ike the one shown. Use the chart to record your observations of different types of tissues.

Observe Take turns looking through the microscope at each type of tissue.

Record Data Record your observations by drawing one ce ll in the tissue. Then

draw several celis, showing how they are arranged.

(»

Communicate With the group, discuss the function of each type of tissue you studied. What part of the body did the tissue come from? What was the shope of the cells in the tissue?

Conclusion 1.

Analyze Data How do all the cells in a single kind of tissue compare?

2. Infer

What can you infer about the functions of all the cells in one kind of

tissue? How would you define tissue?

3.

Draw Conclusions Humans and other animals have a wide variety of tissues in their bodies. What advantage does this variety provide?

Ask Questions You have seen sev"e!"al e~amp l es of animal tissues. Make a list 01 questions yoo ha'/l! about what you saw. Share your list with your class. Choose one question to find the answe!" to in this book, the lillfary, or on the Int!!fne!.

v

af1l by

Reading

Cell Organization

VOCABULARY

MAIN IDEA Cells join together to perform bask life

organ organ system tissue

p.AH p. Al3

functions in mullk ellul,,, org,misms.

p. Al3

Multicellular Organisms Unlike a single-celled organism, a multicellular organism is made up of more than one celL In these organi sms the cells work together 10 perform life processes. The cells are spe<:ializcd, which

READING SKill Main Idea and Details Use a graphic organizer like the one shown to organize the ma in idea and details.

means thaI they perform only certain functions. By working logelher, these cells meet the needs of Ihc organism as a whole. Cells come in many shapes and sizes. The shape

of a cell often relates to its function. Nerve cells, for example, are long and have many branches. This shape allows them to deliver ele<:lricaJ impulses over long dis tances. Skin cells arc generally f1al and arranged close together, In this way, they form a protective layer around the body. Muscle cells are larger than other cells. Their many fi bers can contract and relax to cause movement. Cells in multicellular organisms are organized at different levels. First, they are organized into

In most multicellular orga nisms, cells are orga ni zed as the chart shows. l'

(

~ Tissues

0;>

( ( (

Relaxed

) Contracted

O''Jans

•

...

Organ Systems

) )

Organism

)

... Cell co"~,.

,
to contract and relax. • Lesson 4

... Tissue Muscle celis are bundled to crea te a strong. contracting tissue .

tissues. A tissue is a large group of similar specialized cells. Muscle tissue, for example, consists of long bundles of muscle cells. E.lch bundle of muscle tissue is held together by its own covering. Like their component cells, muscle tissues contract and relax. Similarly, nerve cells form nerve tissue, bone cells form bone tissue, and skin cells form tnc tissues of the skin. A tissue gets its characteristics from the particular type of specialized cell that forms it. Together, tissues of different types make up organs. An orga n is a group of related tissues that perform a specific function. The heart, brain, stomach, and li\'er are examples of organs. EV Cll if two OTg;IllS aT\: nmdc frum the same kind of tissue, they can be \'ery different in appearance and function. For example, bones in the middle car look and function much diffl'n>ntly from the bones in and legs.

Organs arc organized into organ systems. An orga n system is II group of related organs that work together to perform a specific function. Most mult icellular organisms have sever.ll orgnn systems. Organ systems combine to form the entire organism. On the next pages, you will read about different organ systems in humans. They work together to keep you alive and healthy. Plants have organs and organ sys tems, too. Roots, stems, leaves, and frui ts are organs of a plnn t. Specialized tu bes that run through a plant form an organ system called the vascular sys tem. What is a n o.gan syste m7

Organism The muscular system _ . ks with other systems to help the girt lift and grow.

Organ System All of tM sblet~1 mU'SCles mab up ~ (omplu $ystem that mo¥f1S tM body.

Organs tissues make up organs ulled muscles. which pull bones and olfle. parts of the body. Mu~ (l e

----=

Circulatory System The circulatory system is

rt'Sponsible for bringing oxygen and nutrien ts to all the cells of an animal's body. It also takes carbon dioxide and wastes away from the cells. The heart is the ccnlral organ of the circulatory system. The heart is made of muscle tissue that pumps blood. The blood tr.wels to the rest of the body through a network of arteries, veins, and capillaries. Arteries carry blood away from the heart, while veins carry blood back 10 Ihe heart. Capillaries are tiny tubes that connect arteries to \'eins. The capillaries are thin enough to let gases, nu trients, and wastes pass between the blood and body cells. In humans, the heart is divided In to four sections, or chambers. Veins from the body drllin into the righ t at rium. The blood passes to the righ t ventricle, wh ich pumps it to the lungs. There, the blood takes in oxygen and releases carbon dioxide. The blood returns to the heart through the left atrium, then passes to the left \'entricle. The left ven tricle is the la rgest and thic kest chamber. II pumps blood into the arteries that travel to all parts of the body. Most animals have some type of heart and circulatory system, but the structure can vary. A frog's heart, for example, has three chambers instead of four. Fish hearts have only two chllmbcrs. An earthworm has five hearts, ellch with only one chllmber.

1 • l esson 4

Fish two ,imple

two atr ia iIIId

dlamben

one vent, ide

''''''

Human two atria and two ventr icles

Respiratory System The respiratory system brings oxygen to the blood, and removes carbon dioxide from it. In humans and other land animals, the central organs are the lungs. When you inhale, air is brough t into the lungs through two tubes called bronchi (singular: bronchus). Each bronchus branches into smaller and smaller tubes. The smallest tubes l('ad to grapclike sacs called alvroli (si ngular: alveolus). The al\'ooli a~ surrounded by capillaries. Oxygen passes from the alvroli into the blood, wh ile carbon dioxide passes from the blood in to the alveoli. Air moves in and ou t of the lungs so well because of the changing size of the chest. When you inhale, muscles attached to your ribs tighten and pull upward. The diaphragm, which is located at the bottom of your chest, cont racts and pulls downward. These actions expand your ch('st, maki ng mo~ space. Air flows in to your body as a result.

Caterpillar Insects It t in iI" through holes caUed spiracles.

fish brtathe through organs (ailed gills.

The opposite process occurs when you exhale. When the chest muscles and diaphrilgm relax, the spo1Ce in the chest decreases. This forces ai r out of yo ur body. All ani mals need oxygen, so all animil ls have some sort of respiratory system. Insects take in air through tiny holes in the exoskeleton called spiracles. Fish take in oxygen through organs called gills.

Undiges ted food, along wi th water, mucus, and o ther substances, pass to the large intestine. The large intestine absorbs most of the remaining wat('r. In addition, bacteria in the large intestine m:lk(' substances th(' bod)' can usc, such as vit:lmins K and B. An)' remain ing material leaves the body as was te.

Digestive System

You r body cannot use the foods )'ou eat in their origi na l forms. Instead, they must be broken down. The digestive system brellks down food into simpler substllnces. Digestion begins in the mouth. Th('re, food is chewed and mixed with a fluid called saliva. The chewed food then passes into Ihe esophagus and on to the stomach. When food enters the stomllch, cells release gllstric fluid s that brellk down the food further. At the sa me time, the stomach muscl<'S contract mouth __ to mix and gri nd the food. Food then p<1SSCS into the small intestine. C hemicals from the liver and the p<1ncreas enter the first part of the small int<'Stine, where th ey break down food even fu rt her. Cells In the lin ing of the small in t<'Stine produce lldditional chemicals that complete the digestion process. The small intestine is !inC'(] with m illions of tiny, fingerlike projections called villi (singular: \'ilIus). Nutrients from the digested food pass from villi into the blood. p;tn(' U$

Murnan

1 "",1m

Al6 • Chapter 1 • lesson 4

)

Nervous System Have you ever used your big toe to tes t the temperature of bath wate r? In such a case, the toe sends a message up to the brain. The brain interprets the message, then sends a new mess.1ge to muscles in the arms and hands to adjust the hot or cold water tap! Your nervous system takes actions like this all the time. It rffeives and processes information, and it controls how the lxxIy reacts and moves. The nervous system is made of specialized cells called neurons. Neurons receive and send informa tion in the form of electrical impulses. In s.ome ways, neurons act like elfftric wires, although the impulse they cilTry are very different from electricity. The brain is the central orgiln of the nervous system. The human brain is composed of more than 100 billion neurons! Indiv idually, those neurons do very li Ule. Yet working together, they allow your brilin to think, remember, learn, interpret infonnation from the senses, and control movement of your lxxIy. Ex tending down from the brain is a thick cord of nerve cells called the spinal cord. Nerves fan out from this cord to the rest of the lxxIy. The spinal cord is protffted by a thick series of bones called vertcbrile. These bones make up your backoone.

i!

Wh"t "re the import"n t

fuo,;;;~ of the hum"n br"in?

Nervous Systems

Grasshopper Grasshopp~rs have brains, but Can jump

usi n9 onty nervt'S near the tegs.

Earthworm

E",thwofms h"ve reuptors that sense lig ht. touch, vibration. and chemicals.

_ _ ,,'o"t cord

Mus(ular and Skeletal Systems The muscular system of the human body has three types of muscle tissue: Smooth Smooth muscles look smooth under a microscope. They are also called involuntary muscles because they contract without your conscious control. Smooth muscles control breathing. blood pressure, and ffiO\'ements in the digestive system. Cardiac Cardiac muscle is found only in the heart, where it makes the heart beat. Like smooth muscle, cardiac muscle is involuntdry. Sk,l,tal Skeletal muscles, also called voluntary muscles, are attached to the bones. 1hey pull on bones and move them. Skeletal muscles also help shape the body and prot('(t its in ternal organs. Bones are held together by stringy tissues called ligaments, and they are attached to muscles by tough tissues called tendons. Bones, ligaments, and tendons make up the skeletal system. The skeletal system provides shape and support, prot('(ts tissues and organs, and lets the body move. rn addition, blood cells are mllde inside mllny bones. Vertcbrdtes have an intemal skeleton and a backbone. Many invertebrates ha\·e hard externdl exoskeletons.

,." ,10.', '''''''ed

.. A ha.d ,xo~keleton COVtlS

1 • lesson 4

this ghou crab.

Endocrine and Excretory Systems The rush of energy you feel when you are frightened or excited is produced by the endocrine system. The endocrine system consists of glands. A gl and is an org~n that sends chemical messengers called hormones to other parts of the body. Hormones affe<:t the activity of cells far from where they are produced. They d iffuse into the blood and are carried to where they are needed. The body produces many types of hormones. Each one acts on a specific type of cell. Endocrine glands are located throughout the body. The thyroid gland, which is located in the nL"I.·k r"'giun, <';Ulltrub the l>u<.Iy's metabolism, or how cells provide energy. The adrenal glands, which are loca ted above each kidney, are involved in the body's reaction to dangerous or frigh tening situations. And the p~ncreas, which is in the abdomen, main tains blood sugar levels. The excretory system is responsible for removing wastes from the body and maintaining the body's water balance. Re<:all that undigested food is removed from the large intestine. It is the excretory system that ta kes over from the digestive system and flushes the waste from the digestive tract. The kidneys are another important part of the excretory system. They are bean-shaped organs located near

the middle of the back. As blood passes through the kidneys, waste and excess water are fi ltered out of it . They then travel from the kidneys to the bladder and then out of the body. The excretory system plays a very importan t role. Withou t it, wastes wou ld qu ickly poison the body.

~1 \11iiIj.Jt·

What is the rote of the exuetory system?

Excretory System The eKeretory system is responsible for ridding the body of waste.

Other Systems

Keeping Healthy

The human body contains other organ systems as well. For example. the lymphatic system circulates a nuid called lymph. This helps keep tissues free of excess fluid. The in tegumentary system includes the skin, fingernails and hair. The skin has inner and outer layers of specialized tissues. The immune system defends the body from bacteria and o ther discasc-causing agents. It produces antibodies and distributes them

You can follow many simple steps to stay healthy. To kill harmful bacteria, wash your hands often. Always cover your mouth and nose when coughing and sneezing. This will help stop the spread of harmful microorganisms. Eating fresh foods that are rich in vitamins gives cells the nutrients they need. Refusing to smoke or take drugs keeps cells strong so that they can resist infection. Exercising keeps muscles flexible. Exercise also helps you breathe more deeply and your body work effi ciently.

through the blood. An tibodi es are proteins that help fight disease. All body systems work together in many ways. When you exercise, for example, your nerves and musclcs work together to move your skeletal system. Nerves also increase your

~I ' tmli!f'

What is the function

of an tibodies?

heart ratc and slow your digestion, whi le a hormone helps move sugar into your hl<Xld. Usually, all of this

happens without you even realizing it. The body is an amazing machine! Pediatrician

Dermatol09 i St Dodors use x-ray images

to view soO m.

orga ns. ...

r

Orthopedist

,/ Ophthalmolo9ist

A40 • Chapter 1 • Lesson 4

• (ares for young people • admi~islers Va(
LI------ -

Review

o MAIN IDEA What processes take place in the capillaries?

E) VOCABULARY Write a senlence or short paragraph using the lelTllS tissue and organ.

9

Cif
[)ig.. tiv~ Systtm

--F'-

READING SKillS: Main Idea and Details Choose two human body organ systems. Destribe the main function of each.

o CRITICAL THINKING: Apply How are vertebrales and in~ertebrates different from each other?

o INQUIRY SKILL: MUS(ular _-""-'System

Ask Qu estions Give examples of questions that scientists might ask about a cell. a tissue. an organ, an organ system, and an organism .

.emT PREP A major organ of the nervous system is the A. stomach. B. brain.

e.

kidney.

D. lung.

MATH

Make a Graph Research the average body length of horses, cats, and humans. Make a bar graph to compare body lengths to the lengths of the small in testine, listed on p. A36.

Technology Visit w_.edupla(uomls(pl to firld out more about

,,,Iorganization.

HEALTH

Write a Report Research one of the human organ systems (overed in this lesson. Write a report on common diseases that affect the system. Share your find ings with the class. A41

READING

: Compare and Contrast

Vocabulary Complet e each sentence wi th a t erm f rom the l ist.

1. hillllples 01a(n) __ include the sIo:eletal system, respiratory system, and circulatory system.

cell A6

2. A(n) _ is made up of a (1Oup of rtlattd c~1s that wor1r. togethef to perfonn a n..ction. 3. In many c~ls. genetic information is stortd in the _ 4. Water diffuses through the crn membfane by a process tailed _

5. Stroctllrts called __ move a paralTll'(ium mud1 as oars move a boat. 6. Animals and plants are classified in separate _ 7. Single·celled organisms with nl.lClei are I1'lOSt likely _

8. Mushrooms and other __ get their energy by dt'Caying dead organisms. !t.

Unlike other _

n~


..... All orgaotelles AS organ system A33 CKITIosis A17 protins A25 tiuue A33

are not surrounded by membranes.

10. A group of related tissues that work together form a(o) _ ~ Test Prep

Write th e letter of th e best answer choice. 11 . According to tile (~I theory, cells are 13. Protists are usually single-<elled and are always _

""-

A. ~ in plants and .nimals B. largest parts of tile bcxtt C. SIIIiIllest units 01 lift D. SIIIiIllest particles on £arth

12. The kidneys and the bladdtf iofm paf1

of an importan t _

A. specialized B. like aoimak in struaUfl! C. prokaryotic D.tu~

"om

14. Oxygen the air you breathe is transferred to blood ill the _

A. ItvtI of organiloltion B. organ system

A. alveoli of tile lungs B. nose and nasal passages

C. c~ular struaure D. kingdom

C. /\eart D. bone marrow

A«. Ch~'~P"";" '==>-_________________________~

Inquiry Skills 15. Classify Photo A shows a bad~ium. Photo B shows a p."otist. Name one similarity and one diff~ence between the two.

17. Evaluate Suppose someone discovers a new form of bacteria that eats plastic. What might be the good and bad effects of this discovery? 18. Analyze What oth~ body systems does the circulatory system affed? Describe the role of the circulatory system in the body. 19. Synthesize What are four characteristics that scientists can use to compare organisms? List specific examples of organisms that have these characteristics. 20. Apply Smoking damages the respiratory system. sometimes by thickening the walls of alveoli. 'NIla! health problems would a smoker experience as a result?

16. Infer Describe how a disease of the circulatOlY s~tem could harm another system of the body. Give examples of dilferent kinds of damage.

Performance Assessment Diagram l evels of Qrgani:l;ation

Map the Conc.ept

Draw a diagram that sIlows the relationship among celis, tissues, organs, and organ systems in an organism.

The chart shows four categories. Place each word Of term within a category. alveoli chromosome digestive endocrine esophagus immune neuron nucleus smooth muscl e villi

cell

tissue

organ

organ system

lESSON

1

Tiny structures inside these plant cells use energy from the Sun

to make food. How do they do it? Read about it in lesson 1.

Plants defy gravity by making water go up. How do plants move water up stems? Read about it in lesson 2.

LESSON

3

Wild animals and even family pets can help plants to grow. How do animals help plants?

Read about it in lesson 3.

How Do Plants Produce Food? Why It Matters ... Almost all livi ng things need plants to survive. Plants make food and give off oxygen. Animals. including people, eat food and breathe oxygen. The process thro ugh which plants use energy from the Sun to make food makes life as you know it possible.

PREPARE TO INVESTIGATE

Inquiry Skill Experiment WIle n yo u conduct an experiment, you plan and

(affY out an invest igation to test a hypothesis.

Materials • geranium plant with at least 4 1ellves

• squares of cottoo cloth (10cm xl 0cmj

Science and Math Toolbox For step 1, review Making a Chart to Organile Data on page HIt.

2

Keeping Green Procedure

o Collaborate

Work in a small group. In your Science Notebook, draw a cha rt like the

one shown. Use the chart t o help you test this hypothesis: Plant leaves need sunlight

e e e

to stay green.

Experiment Place your plant in a sunny window or plant it out side in a sunny,

sheltered spot. Use the doth squares to cover at least three leaves. Leave at least one leaf uncovered to serve as a control. Predict How do you think t he different leaves will change over time? Record your prediction.

Record Data Check the plant every day and give it water if t he soil is dry. Every two days, re move the cover from one or

e

more leaves. Record your observations, then cover the leaves again. Analyze Data Discuss the differences that you observed and recorded. Compare the effects of blocking sunlight for two days, four days, and si x days.

Conclusion 1.

Use VarialHes What was the variable in this investigation? How did you change it? WhClt was the control?

2.

Analyze Data Review the hypothesis and your prediction. Did you find evidence to support the hypothesis? Explain why or why not.

Investigate More! Design an Experiment Plan and conduct an experiment on plants that tests anothe-r variable, such as water or soil quality. Des<:ribe the control in your experiment.

\.eat~ by Reading

Prod

Food

VOCABULARY

MAIN IDEA Plants uS
chlorophyll chloroplast pho t osynthesi5

f ood. They combine carbon dioxide am:! w at er t o make

stomllt.

..,,,"" p. "51 p. /l.Sl

READING SKILL Seqllenu Ike iI chart to show tile Si!qU!'IK1' of steps in photosynthesis.

(

( (

• •-

)

) )

sugar, .md re lease oxygen in the proen s.

Photosynthesis You aTe constantly using energy to conduct all of you r life processes. You need energy to breathe, ea t, move, thin k, and even sleep. The energy you use ul timately comcs from the Sun, Recall from Chapter 1 that pla nts transform the energy of sunlight inlo chemical energy stored in food. Plan ts, lliong wi th some protists and bacteria, accomplish this through a process called photosynthesis. During photosyn thesis, plants combine water and ca rbon diox ide into compounds called sugars. They release oxygen in the process.

'" Plant cells (on tain Ofganell~ (ailed dlloroplasts.lnside them, light energy is changed 10 cMmlc.a1 energy.

Sugars aTe a plant's food. The plant stores sugars in its tissues and breaks them down when it needs energy. When an animal eats the plant, it can uS(' the stored sugars. And when a larger animal eats the plan t-eater, it too obtains energy originally stored in plants. In this way, all anImals depend on plants for energy. In Chapter 1 you learned that photosynth esis takes place in organelles called chloroplasts. The number of chloroplasts in a cell depends on the organism. Some tiny algae cells have only one chlo roplast, while the cells in the leaves of a tree m(lY each contain more th nn fifty. Most chloroplasts have the Solme basic structure. Each is surrounded by h\'O membranes. Another system o f membranes courses through the interior of the chloroplast. These membranes look like fl at sacs arranged in stacks called grana. Inside the membranes are a variety of pigments. A pigment Is a substance that absorbs light. The most importan t pigment in a chloroplast is chlorophyll.

A In~lde a chloroplast. ~ta(ks of

membranes called grana (ontain chlorophyll, which absorbs ~unlight.

Chlorophyll absorbs most colors of light, but not green. This means that when sunl1ght hits chlorophyll, grem light is reflected to you r eye. This is why pl;m t parts that contain l(lrge amounts of chlorophyll look green. How does photosynthesis work? When light strikes chlorophyll, the energy is used to split apart water molecules into hydrogen and oxygen. Later, during a series of chemical reactions, the hydrogen joins with ca rbon from carbon dioxide to form suga rs. The oxygen gas is released. Photosynt hesis is a unique process, and it's hard to imagine life on Earth wi thout it. The nexl time you look at a tall tree or other p lant, remember that almost all of its matter came from only water and carbon dioxide.

~"(.jIn:!J'

What happens during the p4"O(ess of photosyn thesisl

'--------

leaf Types Many bladM

Plant leaves In almost all plants, leaves hold most of the plants' chloroplasts. You can think of leaves as the food factory for a plant. Plant leaves come in many different shapes and sizes. They can be round or heart-shaped. They can be smooth or have jagged edges. The bro.1d, fla t portion of a leaf is called the blad;>. Sci;>ntists group leaves by the structure of the blade. A simple leaf has a blade that is one piece. Oak trees and apple trees have simple leaves. A compound leaf has a blade that is divided into parts. Rose bushes and palm trees have compound leaves. Leaves are made of different tissues. The outer layer is ca11ed the epidermis. The cells in this tissue have a waterproof coating that prevents wat;>r loss. Remember that a plant needs to exchange gases with its environment. Small openings in the epidermis allow oxygen and carbon dioxide to enter or leave the cells. They also allow water vapor to leave. These openings are called stomata, and are scattered about the underside of the leaf. The word stomata comes from the Greek word stoma, which means mouth. You can see from the picture that stomata look like small mouths. Specialized structures that act like gates control the opening and closing of the stomata. When they open, carbon dioxide enters the leaf while oxyg;>n and water vapor ;>xit. • Lesson 1

Simple Leaf

Compound Leaf

A simple leaf has a single blade. The larger its wria<e area. the more sunlight it {an take in.

A compound leaf has many blades. This leaf type may promote gas e ~ {hange .

Stomata often open during dayligh t when photosyn thesis occurs. At night, stomata usually dose to keep water In. Stomata can also open and close in response to Changes in the environment. During dry spells or on hot days, a plant's stoma ta might stay doS<'d to conS<'T\'e wa ter. Most of the cells that perform photosynthesis lie just below the epidermis. These cells arc arranged wilh many air spac;>s between lhem so that carbon dioxide, oxygen, and wa ter can flow freely. Coursing through I;>aves are long, thin structures called veins. Veins carry mat;>rials in and out of the leaf, serving to connect the leaf's cells to the rest of the plant. You will read more about this structure later in this chapter.

~11(,j1IM' leaf arranged?

How are the tissues of a

Energy

Energy 01 sunlight powers the pro(ess 01 photosynthesis.

Water Water is transported up the plant into the leaf. Chloroplasts Chloropla
.rOxygen dioxide

.... Stomata like gate keepers. stomata open and close to let gases in and out of the leaf.

Vapor

lowe • epidermis

2.200 >.000

,,"00 ••• -•••• '.'" •• 1 •0 '.'"

, · .-

'.'" '.000

•~ •

- ..,..,

0=

."

... "E

•

1980

,., • A"",. i
"" ~

Carbon and Oxygen Cydes Why doesn' t the air run out of oxygen, or fill up with carbon dioxide? The rcason is tha t oxygen (lnd carbon dioxide cycle through the environment. As yOll have read ,

plants take in carbon dioxide and give off o xygen. Both plants an d (lnimals use oxygen to brea k down

sugars. In the process, they release carbon dioxide. Together, pla n ts and llnimals re<:ycle thl.' gases they both "eed. Human activities can upse t the carbon and oxygen cycles. Fossil fuels, for example, contain stored carbon. When people burn these fuels, induding coal, oil, a nd na tural

gas, the carbon is released as carbon dioxide. • Lesson 1

Region

Both carbon dioxide and oxygen cycle

throu!lh

pl~n's. ~nim"ls..

and Earth's

atmosphere. Cutting down forests can upset the balance that this qcle provides. Unfortunately, deforestation continues all over Earth.

Today, people are burning fossil fuels at a very fast rate. The result is a rapid return of carbon to the atmosphere. [n addi tion, people are also cutting dow n forests, including wide tracts of rain forests in South America and other places. This means that fewer trees are available to remove carbon and release oxygen. ~ SlQUlNCl

How do carbon and o>
cycle through the atmospllere?

Review

o MAIN IDEA What are the two

main products of photosynthesis?

During

photO'lynth e~is.

plilnt~

and so me oth er organisms use carbon dioxide and water to make sugars and release oxygen.

E) VOCABULARY Wr ite a short paragraph using the terms chloroplast and stomata. Describe the ro le of these SlIuctures in photosynthesis.

€) READING SKILL.: Sequence The green pigment chlorophyll is found in chloroplasts. This pigmenl absorbs the energy in sunlight to power photO'lynthe~is.

Plants and ilnimal~ cycle carbon and oxygen th rough the environmen t.

Describe the purpose and steps of photosynthesis. Why is this process important to all life 00 Earth? O CRITICAL THI NKING: Infer A typical (aduS has a green stem and th in, spike·like needles that are not green. In which of its parts does a cactus pefform photosynthesis? Explain.

o INQUIRY SKILL: Experiment

Do house plants aHect the quality

of air in a house? Desuibe an experiment to answer this questioo. What gases would you want to measure?

MATH

(reate a Formula Suppose tha t a forest produces x amount of orygen per day. Write a formula for the amount of oxygen a fo rest half the size would produce in a year.

SOCIAL STUDIES

MakeaMap Rain forests and other forests contain a large percentage of the green plants that live on dry land. Research more about the world's forest reSources. ( reate a map showing whe re they are, how big they are, and how quickly they are disappeari ng.

.tTEST PREP In leaves. what do celiS just below the epidermis do?

A. Produce hydrogen gas B. Store nUllients

C.

~rform

photosynthesis

D. (reate fossil fuels ~ Tec.hnology 'iii Visit w_.eduptacuom lscpl to fond out more abooJl plants and photosynthesis.

Readers' Theater

IH o How do people use

IS plants~

The setting is the

Chung family living room. Ben reaches for the remote (ontrol to find something worth watching. However, just as he's about to

change channels ...

Characters TV Announcer Ben Chung:

A fifth-grade boy

Julia Chung: 8en's sister

A girl

Dr. George

Washington Carver: Scientist

Dad: Ben and Julia's father

( AS6 • Ct.ilpler 2 • l HSon 1

,

READING Announcer: Stay tuned for our next program, "The World of Plants." Ben: (yawning): Do you mind if I find something else to watch?

Announcer: We're at a rubber tree plantation in Brazil. You can find farms like this in tropical regions all over the world. Ben: (pressillg on a 1,,'1'): These trees don't seem bounder than other trees.

Julia: Go ahead. This show sounds really boring. Announcer: You're quite wrong, Ben and Julia Chung of 333 Portland Road!

Dr. Galvez: (enlering): That's because rubber comcs from the sap of a rubber tree, not from the wood.

Ben: Julia! Did you hear that? He's talking to us! (Bell and Julia Iet/n loward

Ben: Who are you?

ti,e TV.)

Dr. Galvez: I'm a research chemist. ! study ways to change raw rubber into sturdy, useful products.

Announcer: That's right. Plants aren't boring at all. In fact, some Me quite surpnsmg. Julia: Surprising? I doubt it. I already know all about plants and how important they are. Plants make the food we cat and add oxygen to the air we breathe. Ben: And trees give us wood and paper products. So you see, we already know everything. Can we please change the channel now? Announcer: Hold on! Do you know that rubber comes from trees, too? xl'ne 5wilc/,es quickly 10 a grove of mbber IfI.'1?S. Birds, mal/keys, and oilier allimals c/mlter ill IIII' oockgrolilld.

Julia: Where arc we?

Julia: Like what? Car tires? Dr. Galvez: Ycs. And many other things, too----escalators, rain gear, windshield wipers, and even pendl erasers. Ben (lookillg arollnd): I'm glad you're putting these rubber trees to good use.

~-

Rubb er Tile rubber in most tires begins ~s sa p in rubber t le~

Dr. Galvez: Oh, yes. Today, people usc more rubber than ever before. To meet the demand, scientists are mi xing natural rubber wi th rubber made in laboratories.

Emily (ell/ering): Allow me to answer. I'm Emily, lind this is my farm. Oil from jojoba seeds is used in shampoo and mll keup. Resellrchers are studying how to use it liS a fuel, too.

Announcer: Than ks, Dr. Ga h'ez. lime to meet nnother interesting plan t.

Ben: Li ke gasoline or diesel fuel?

Julia: Now what?

Emily: Yes. Think how useful that migh t be! Instead of digging up fossil fuels, we might raise plants li ke the jOjObll.

Announcer: Welcome to Arizona. Meet the jojoba plant.

Julia: I bet the seeds grow year after year, too. We'd never run out of them!

Ben: It looks li ke an ordinary shrub tome.

Announcer; Ahll! Maybe now you believe me when I say plants can be surprising! Did you know thll t citronella oil cOme~ from dried grasses? People use it to repel insects, especially mosqui toes.

Scerle swilc/,cs 10 a t/es.>rl.

Announcer: Maybe so, but take a look at these seeds. They're filled wi th a very un usual oil. Julia: What's so unusual about it?

Jojoba (ho HO bal •

Sh~mpoos

and

~in

lotions • A pote ntial fue l

( AS8 • Chapter 2 • Lesson 1

Bamboo

Foxglove

Peanuts

• fences and paneling • furniture and 1100' mats • Decora tion and art

• Oigitalis. a heart medicine

• food and cooking oil • Paint
)

Emily: Don't forget s..1P from the chicle trcc. It's used to ma ke chewing gum! Dr. Galvez: How abou t so,1pwort? It's used to make soap that cleans delica te fabrics. Dr. Carver: (I'IItl'riug): Hello, everyone. I'm Dr. George Washing ton C;uvcr. I'd like to remind you about another important plant: peanuts. Why, I invented more uses for peanuts th;m anyone ever imagined! Today, peanuts are used to make ink, grease, shaving cream, paint, construction materials-

... Soap ' rom the soapwort plant is used to clean valuable tapestries.

Ben: OK, O K! I' m convinced! Plants aren' t boring!

Dad (slrllkilJg ikllllud Julill gelllly): Hey, wake up, kids!

Julia: They're downright amazing!

Ben and Julia: What? What happened? Dad : You slept through a TV snow abou t plants. I came in part way. I though t plan ts were dull, but I was wrong! Why, did you know ... (BI'IJ

flmIJulill/flugh')

Sharing Idea, 1 RfAOIHCi
uses fOf plants?

2. WRn'EABOUTIT Whatarethe advantages of using fuels from plants instead of fossil fuels? Or. George Washington Carver (1864-1943)

1 TW ABOUT IT What other products

come from plants?

How Do Plants ove Materials? Why It Matters ... Plant leaves need water and minerals that are found in soil. Without them, photosynt hesis (o uld

not occur. Almost all plarlts have a way to move materials upwards, against the downward pull of gravity.

PREPARE TO INVESTIGATE

Inquiry Skill Predid When you predict, you t ell w hat you think will happen. based on your knowledge

of previous cause-and-effect pattern s.

Materials •

~ pl~nl

with (II

1~(I~t

4 L>rOdd

leaves • petroleum jelly • 4 plastic sandwich bags with twisllies

Science and Math Toolbox For step 1, review Making a ( hart to Organize Data on page H11.

These pails catch sap from maple trees.

Losing Water Procedure

o G

o

o "

Collaborate Work in a small group. In your

Science Notebook, draw a chart like the one shown. Experiment Carefully smear petroleum jelly on the top and underside of one of the plant leaves. Coat another leaf on t he top surface only. Coat a third leaf on the underside only.

Experiment Slide a bag over each of the coated leaves and close it with a twist tie. Cover a fourth, uncoated leaf with a bag, to serve as a control. Label eClch bag.

Tim .

,

~.

, ,

.~ .

~.

..,, ,

".

Place the plant in a sunny window and, if needed, water it.

Predict Based on what you have learned

about leaf structure, predict what will happen inside each bag. Record Data Check the leaves every hour

for three hours. Use the chart to record your observations.

Conclusion 1.

2.

Analyze Data With others in your group, discuss reasons for your results. Consider different explanat ions.

Predict Based on your results, discuss with your group what will happen if you leave the bags on t he leaves for two more days. Give reasons for your prediction.

3.

Experiment Continue the experiment for two days or longer. See if your prediction holds true.

Investigate More! Design an Experiment Plan a similar experiment with a different kind of plant. For example, you might choose a cactus or an evergre1!n plant.

"earn by Reading VOCABULARY nonvas
MAIN IDEA PI"nts have spedalized tissues and use

p. Ml

p,A6, .", p,A63 p. .0.63

READING SKILL Text Structure Use the headings in this lesson to

identify the ma in ideas of the text.

Materials natur,,' forces to transport wilt e r, miner"ls, and nutrients.

Nonvascular Plants If you have ever observed moss on the side of a tree, you know that not all plants have the same structures. Mosses are examples of nonvascular plants, wh ich lack true leaves, Siems, and roots. They also lack structures that transport food, wa ter, and other materials between plant pariS. In addition to mosses, nonvascular plants incl ude liverworts and hornworts. They have few spedalized cells and no complex organs. Nonvasculnr plants are almost always small. Thei r size is limited because they lack ways to deliver water to dis tnnt parts. Instead, mos t of their cells must be dose to the outside environment. Gases, water, and minerals move directly between the environment and the cells. Although they are small, nonvascular plnnts fill important roles in their environments. 6e<::ause they absorb water, they help hold soil in place and keep it from drying ou t.

Mosses a nd Liverworts Nonvascular plants have no complex organs. Some of their leaf·like tissues are only one cell th ick.

Vascular Plants

Trunks and Stems

Most plan ts you can name, including evergre('n tll2'C$, flowering plan ts, and ferns, are examples of vascular plants. A vascular plant has special ized tissues that transport materials throughout it. Veins, whk h you read about in Lesson I, carry materials in and out of le,wes. Veins are examples of vascular tissues. The organs of vascular plants include roots, stems, and leaves. Roots anchor a plant in the ground . They also absorb wa ter and minerals from the soil. Some roots store food for the plant as well. The stem sup ports the plant and holds its leaves up in the air so they can re<eive sunlight. The stem also provides a way for water, minerals, and food to move between th e roots and the lelwes. Stems contai n two important kinds of tissues: xylem and phloem. Xylem tissues conduct water and minerals upward from the roots. Phloem tissues conduct food materials downward from tnc lea ves to tnc rest of tnc plant. A typical plan t stem has a ring of bundles containing both xylem and phloem. A strip of tissue called the vascular cambium lies between the xylem and phloem. Here, xylem and phloem cells are produced.

f} TlIT STRUCTURE of vascutar t issue?

What are two types

Trunks Growth rings mark each year's IH!W xylem, or wood tissue. The darker parts show wtwe growth slowed at the end of each season.

v~ scul ~r

Stems Stems grow wider by adding new layers of xylem and phloem. New layers grow on either side of the vascular cambium .

·~--------------------------~CA~'~')

Gravity

The Upward Flow of Water

N:lod from

Usually, water flows downward . In thc s tems of plants, however, water flows upward. How does this happen? Water moves up in plants because of root pressure, cohesion, and transpiration. Water en ters roots because roots are dryer than the surrounding 5Oil. The outer walls of roots have specialized cells tha t keep Ihe wa ler from leaking back out. Eventually, pressure builds and pushes water upward. Root pressure alone is not strong enough to pu~h Wille r throuSh an rntirc plllnt. Water travel s the rcm;lindcr of Ihe trip tx-cause it is

; is pulled down 10 nourish th~ plant

W.t~, and minerals ding to e3Ch other and to tht "flem walls. This forms a

Cohe5ion

(olumn un~r I~n.lon

that rises up the stem.

pulled upwud. Wlltcr molecules ding to each o the r as a resul t of 11 force called cohesion. They di ng to molecules of other substilnccs, too, and this force is called adhesion. This forc:es water to climb up lubes of xy l('m ti ssue. An additional pull is needed to move waler to Ihc tops of taller plants. That pull is provided by tr.mspiralion. During transpiratio n, evaporation occurs through the leavcs of a plant. As wa ter movcs from the plnn t to the air, water is pulled upward through the plant to take its place. About 99 percen t of the water that enters the roots is transpired by the leaves! TUT STlUCTUftl

What all! thrH fortn thaI

move wat~ r up tn a plant?

A64 • Ch.aple. 2 • te-sson 2

Root Pressure Root prHsurf

pushes wate r and minerals up.

Review

o MAIN IDEA How do force'! push Nonv~s(ul~r plants do not have vessels to transport water and nutrients.

and pull materials through a plant?

a VOCABULARY Write a short

paragraph using the terms xylem and phlDli'm.

o READING SKill..: Text plants have specialized tissues called xylem and phloem for tran~portin9 water and nutrient~.

Structure List three details about either xylem or phloem.

V~s(u l~r

O eRITICAL THINKING:

Hypothesize Suppose you coated the leaves of a vascular plant with a substance that prevents transpirati(l!l. How would this aHeet the movement of water up the plant?

Water is moved upward in a vascular plant by root pressure. cohesion. and transpiration.

Q INQUIRY SKILL; Predict

Explain how materials in pesticides in the ground might end up in a plant's leaves.

.jJ TEST PREP Evaporation from plant leave'! is called

MATH

Make a Graph Mix several drops of food (Oloring into a beaker of water. Place a tall celery stalk into the beaker. After every 5 minutes, measure the height that the colored water traveled up the celery. Make a graph to show the data. What conclusion can you draw from your results?

WRITING

Expository Research the story

of maple syrup. Write an essay that shows how maple syrup is made, packaged, and delivered to your table.

A. root pressure.

B. transpiration.

C.

OSmosiS.

D. cohesion.

~ Technology

'Ill

Visit w_.edupta(uomlscpl 10 fond out more aboor .aso:ul;rr iIIId nonvaso:ular plan!!.

How Do Plants Reproduce? Why It Matters ...

PREPARE TO INVESTIGATE

Many people enjoy flowers for their bealltiful shapes and colors, and for their pleasant scents, Such

Inquiry Skill

qua lities are no acddent, Plants use their flowers to attract animals, and the animals help the plarlts reproduce.

Analyze Data When you anal yze data, you study the information you collect, looking for patterns that might lead to a hypothesis

or to a conclusion.

Materials • flower • white paper or paper towels • plastic kn ife • hand lens

Inside a Flower Procedure

o e

e o

e (»

D"'wing of Outer 5~cw

...e

DraM"!!

of Indl.:l~ 5~cw,"

Collaborate Work in small groups. In your Science Notebook, make a chart like the one shown here.

Observe Place the flower on the white paper and observe it carefully. Use the

hand lens to see details.

Re<:onl Data Sketch the outside of the flower. Add labels to show colors, textures, and the numbers of each kind of structure. Experiment Using the plastic knife, carefully slice the flower in half from top to bottom. Record Data Sketch the inside of the flower. Add labels to record details. Communicate Compare sketches with other group members. Discuss any differences you see. You may revise your sketch to make it more accurate.

Conclusion 1.

Analyze Data Were the same structures visible on the outside and inside of the flower? Explain.

2.

Infer Why do you think plant scientists study the insides as well as the outsides of plants?

Inve'Stigate More! Design an Experiment Plant seeds of field mustard plants or other last·growing plants. Provide the plants light, water, and warmth. Observe and r«ord the stages of their life cycle.

v

afll by

Reading

VOCABULARY

Plant Reproduction MAIN IDEA PI"nls reprod uce !,Ising spores or seeds.

angiosperms

p. 1I.70

gymnosperms

p,.o.69 p,A69

.'"

pollinat ion spores

READING SKILL Comp a~ and Cont rast Draw a Veon diagram

to show how two types of plants are alike and diffenmt.

They are d ispersed in di ffe re nt w"ys.

Seedless Plants and Conifers A plant's pattern of genera ti on, growth, and

reproduction is known as its life cycle. Scientists classify plants into two major groups according to their life cycles. One group is the ~ plants, which reproduce with seeds. The second group is the seedless plants, which reproduce wi th s pores or other structures.

Fern Life Cyd e Spores

The wind scatters

Sporangia

mature spores from the sporangia.

Gametophytes Some SpOrfi g.ow into st.uctu.es that p.odlKe

g:;~:,:;~;,::, male and f.

"

Spores are produced in sporangia on the

undersides of flonds.

Fern Tile zygote will gro..... into a mature lern ,

• Lesson 3

( Male and female cells join to form the zygote. a process called fertilization. A new plan! begins .

One common seedless plant is the fern. Ferns grow throughout the United States, but they grow best in warm, moist climates such as in tropical rain forests. Let's take a close look at its life cycle. Most large plants are seed plants. Scientists further divide the seed plan ts into two IMge groups. Plants wi th seeds that are not covered by a protective fruit arc called gymnosperms, which means "naked seeds." Conifers, such as pine, spruce, cedar, and redwood trees, are the most common of the gymnosperms. The seeds of these conifers develop inside cones. Conifers pTtXluce both male and female cones. Male cones Me smaller. They arc often located ncar the tips of the bwnch ....s. FcmuJc COI1L"S arc generally larger. Some types of conifers produce both male and female cones on the s.ame plant. O ther types of conifers have male and female plants that each produce only one type of cone. Male cones produce pollen. Pollen is reproductive material that contains male gametes, or sperm cells. Female cones, called seed cones, contain ovules. Ovules contain female gametes, or eggs. In the spring, pollen cones release millions of tiny pollen grains in to the wind. Man)' pollen grains fall to the ground or land on water. But some Me blown on to seed cones. Any process tha t delivers pollen to eggs is an example of pollination. With conifers, the wind or air is the agent of pollination.

Once the pollen grain lands on a seed cone, it releases sperm cells. These sperm cells can fertilize the ovules. This forms a new zygote, which can divide and develop into seeds. When the seeds mature, the), arc released from the cone. If the conditions are right, a seed will develop into a new conifer.

~ (OMPUE AND (ONTAUT diffe.ent f.om conifers?

Pine (ones produce pollen (in the male cones) and ovules {in the female (ones). Seeds develop in the female (one.

How a.e fe.n5

Flower Life Cycle Gennination Gf rmination o«u~when a ~ed SprOtlts into a nfW plant.

.....

Fruits are mature plant ovaries. whi ch expand to protect and nourish se-eds.

Flowering Plants The second large group of seed plan Is are the angiosperms. An angiosperm produces seeds within a protective covering. Angiosperms are also called flowering plants because they store seeds inside flowers and fruits. The flowering plan ts make up the largest group of plants in the world. In filct, nine out of ten plilnt species ilre flowering plants. Flowers ilre the reproductive organs of angiosperms. They have many parts, ilnd eilch has a purpose relilted to reproduc tion. The male reproductive organ is called iI stamen. Two parts make up

( A70 • Chapter 2 • Lesson 1

Fertilization fert ilization takes place inside the ovary. whet! a male gamete from the pollen joins a female gamete in the ovary.

the stamen: a thin filamen t, or stalk, ilnd iI rounded iln ther. The anther produces pollen, or male gametes. The female reproductive organ of iI flower is called the pistil. Pistils ilre found in the center of a flower. Three parts make up the pistil: the stigma, the style, and the ovary. The stigma is the sticky tip of the pistil. The style connects the stigma to the ovary. The ovary contains one or more ovules. Keep in mind that nol all flowering plants are identical. Some flowering plants make both male and female reproductive organs in the S<1me flower. In other plants, they are mildc in different flowers.

Flowers contain tile reproductive parts of the plant.

J

Pollination Pollen from the male anthe r ruche~ the femal e ~tigma.

The colorful. leaflike structures of a flower are called petals. Flower petals surround and protect the male and female reproductive organs. They also play an impor tant role in pollination, as you will find out soon. In flowering plants, pollination occurs soon after a grain of pollen lands on the sticky stigma. If the pollen is from the righ t type of plant, the pollen produces a tube that grows through the style and into the ovule. A sperm cell is released from Ihe tube to fertilize the egg cell in the ovule. The resulting zygote develops inlo a seed that may eventually be<:ome a new plan t.

As the seed develops, the ovary changes to be<:ome a fruit. The fruit prolects and nourishes the seeds. Fruits also attract animals that help spread the seeds. The frui ts you eat are matuTC ovaries that surround the seeds inside. These fruits include apples, oranges, cherries, and berries. They also include some foods you may not thin k of as frui ts, such as tomatoes, peppers. and cucumbers.

~ (OMPUE ANO (ONTIIAST

How do angiosperms differ from gymnosperms7

A11

Pollination Pollen ca n be dispersed in many ways. Here are some examples. Self-pollination [n some plan ts pollen can move directly from the male parts to the female parts. In peas and beans, for example, a single flower contains both parts. Wind Some plants release pollen into the w ind. These plan ts usually produce large amounts of pollen because much of it will be wasted on the ground or in water. Plan ts that depend on the wind often have structures that expose the pollen to the a ir. For example, some plants have very long stamens that reach into the open air. They also may have stigma with feathery arms tha t catch pollen from the air. Corn is one example o f a wind~ pollinated plant. Male parts are located ncar the top of the plant, where the wind can catch the pollen. Female parts arc located farther down the plant.

,...-

Hummingbirds have long. thin beaks that allow them to reach the nectar inside narrow flowers. A

Water Some plants live in water and use wa ter to carry pollen. The pollen gra ins f10..1t from male parts to fema le parts. Sea grasses use this method of pollination. Animals Flowers that have bright colors or s trong fragrances are usually pollinated by animals. The colors and scents allract animals that come to feed on a sugary nectar that the flower produces. As the animals gather nectar, pollen becomes stuck on their bodies. The pollen is deposited in different flowers as the animals move among them. Hummingbirds, bats, bees, and butterflies all pollina te flowers in this way. Farmers who grow fruits often raise bees as wel l. Bees help pollinate the trees and they ma ke honey. ... Honeybees have thick leg hairs that pollen clings to.

Seed Dispersal Like pollen, ptant seeds are also dispersed by different means, Wind I-/,w(' you watched the feathery seeds of a dandelion f1o.1t through the

wind? Dandeli ons, orc hids. and olher plants ha"e small, ligh t seeds tha t winds easily carry. The sc.>eds of black milple trees are oo\'crE'd by thin, dry fruits that ad as propellers.

Watt r Some plant seeds and fruils lire spread by water. TheS(' fruits and seeds con tain air chambers tha t help them to float. The large fruits of the coconut palm, for example. can float great distances on ocean currents. This is why coconut p.llms often grow on small tropical islands. An imals If you have c\'cr had

OJ

hurr

stu ck on you r clothing, you may

have helped to disperse pl
" Do you Sei! the burrs on this dog? Each burr hol ds seeds. The dog helps spread them away from the parent plants.

Many animals are attracted to the sweet taste of many fruits. As the animal eats the fruit, it may disturb so me of the seeds. The seeds drop to the ground where they may grow into new plan ts. Animals can also help spread seeds by eating fruits. Some seeds pass through an animal intact, and thus Ix-oome part of its wasle. Fruiteating birds often spread plant seeds in thIs way. What a.e i ways t hat poll en and seeds a' f! dispersed1

.. Sud dispersal un depend on wind, but an imals are also efficient at spreading seeds.

Flowers Gra~~es

• many smalillowers clustered together • lIowers can be arranged in ma ny different ways Sunflower • head is made up 01 many ~malillowers • each II(lW(!r produces

~

"'"

(om • clusters of male lIowers {ailed tasseis • fl'm
fnIits and

s •••

Avocado • Ileshy Iruit • one la rge se-ed • seed imide fruit Orange • Ileshy fruit • many small ~ • se-eds located in (Oi!'flter Strawberry • lIeshy fruit • many tiny seeds • se-eds spo-ead throughout surface

"-

Variety in Flowering Plants Angiosperms grow in most places on Earth _A fcw species cvcn live in ocean wate r. Angiosperms around the world have developed an amazing variety of structures to help them reproduce in their environmen ts. Flowers exist in many di fferen t sizes, shapes, and colors. Water lilies have some of the largest flowers. Clover, sedges, and grasses have some of the smallest. The most common flower colors are red, yellow, w hite, and blue. Fruits also exist in many sizes, from tiny berries to large coconuts. Fruits grow around different kinds and numbers of seeds. Pomegranates have many tiny seeds. A grape or A74 • Chapter 2 • Lesson 1

apple might havc two or three seeds. A cherry or avocado has only one >«d. People have lcarned to ta ke advantage of this variety in flowers, frui ts, and seeds. Humans eat not only seeds and plants, but also flowers . Cauliflower and broccoli arc examples of flowers that people eat. Farmers plant seeds at the start of each growing season. The ability to grow crops from seeds has helped humans thrive and flourish for thousands of years.

~ (OMPARE AND (ONTUST

How do people t"ke "dvant"ge of the v"rie ty in fl owers, fruits, and seeds?

Review

o MAIN IDEA What are the most

Visual Summary

numefOUS types of plants?

f) VOCABULARY Wr ite a sentence An9io~ms

or short paragraph using the terms gymnosperms and

angiosperms. 'ep'od"..

•

b\'

spo'ong",

• ~

'eproduce b)'

,-

•

f) READING SKill.: Compare

•

o CRITICAL THINKING: Apply

FI..-"

~

...

0' Wow

and Contrast What do sporangia, cones. and flowefs have in common? How are they diffefent? Explain why many gardeners plant flowers that attract bees and butterflies.

o INQUIRY SKILL: Analyze Oata Give three reasons why angiosperms are the most successful plants on Earth .

.tTEST PREP

MATH Make a Xile Drawing

Suppose a bee~per has 180 acre'l of clover and 9 honey~ hives. How many acres must each hive pollinate in order for the clover to reproduce? Make a scale drawing of the farmer's land, showing the location of each hive and the size of the plot of land it is on.

TECHNOLOGY Make a Poster Research ways that farmers depend on inse<:ts to help in crop pollination and reproduction. Make a poster that features one kind of inse<:!. Show how it helps farmers.

All flowefing plants prodlXe seeds and A. fruits.

B. other edible parts.

C. brightly colored petals. D. sporangia. ~ Technology 't!!i Visit w_.edupla
'!'P'oou<1ion.

Is it a giant worm from outer space? An undersell erell'ure? No, you' re looking lit a mllgnified burr- a tiny seed with hooks. Mllny plllnts depend on wind lind wllter to scatter their seeds. Others rely on IInlmals to lell\l'e them in droppings, But burrs are hitchhike rs. They travel by hooking themselves onto animals' fur- and people's clothlngl Through a microscope, you can see a strong resemblance betwe en a burr and a strip of the hooked faste ne r clilled Velcro' M • This is no coincide nce, Inventor George d e Me stral got the idea for the tiny hooks of Ve lero' M from studying the clingy burrs that he plucke d from his dog's fur. s""'~ pl~nt spe< les, lih (o(kle bum, have lite rallv hit(hhiked anMS North Am eri(a and Europe.

Crab a ride!

READING

Super cling! Burrs cling tight, and so does Velcro - . A piece of Velcro '~ the size of two hands can support the weight of a small car!

: Compare and Contrast

Vocabulary Complete ea( h se ntence wi th a term from the list. 1. The green pigment in plants is c~led _

angiospt"n, A70

2. The process by whim plants use solar energy to make load

chloroptlr11 ASl chloroplast ASl

is _ 3. Openings called __ let ail' and water in and out 01leaves.
5. Tiswes known as _ its leaves.

transport water from a plant's roots to

6. The plant tissUl'S that trallSpOfl ootrients <1'Nay from the leaves are _ 7. The process of __ takes place when evaporation occurs

through the leaves of a plant.

gymn
nomoascular P',lIIt 1162 ......... "3 photosyntltHis MO pollination A69 ....K A68

stomata A52 tr,lllspiration A6-4 v,lSw'ar pl,lIIt A63 xylem A63

8. Seedless plants reproduce by releasinq _ 9. The process 01 delivering pollen 10 eggs is called _ 10. _

I

are plants that produce seeds with a protective covering. Test Prep

Write th e letter of the best answer choice. 11 . Chlorophyll has the ability to _

A. tr~ <arbohythlH B. po-otect tilt ctll from the Sun C. absoIto 190t ftlI'i"9Y D. build tel ~Is

12. People rely on photosynthesis in plants fOf food and _ A. olC'f9l!l1 B. carbon dioxide C. chlorophyll D. minerals

A78 • Chapter 2

13. Some nonvilS
ability to _

.....

A. transport water iItld minerals through 8. help control moisture in lhriI_ioolimtnts C. rk!o.oelop strong stems iItld leaves D. prodUCt >:yItm iItld phloem 14. Angiosperms procb:t their ~metes

inside _ A ,,,,,,,,"

B. ~angia C. cones D. stems

Inquiry Skills

Critical Thinking

15. Synthesize 1000tify at least two fu nctiOlls for each of these plant parts.

11. Apply Why do moss plants grow best in damp places, such as the floor of a forest? Would mosses grow well in dry. sandy soil? Explain. 18. Analyze l ist three different ways that seeds are spread from place to place. and indude OIle example of each. Why is seed dispersal important to plants? Why is it important to humans?

16. Experiment Describe an experiment that would help show which plants attract butterilies. Propose an hypothesis about whether butterflies are attracted to a specific color or shape of flower.

Map the Concept The chart shows thr~ processes. Place each

word or term in the correct column. Some words go in more than OIle categot)'. chloroplasts fruit gametes germination oxygen solar energy

Photosyntl>esis

stomata cohesion evaporation water fertilization root pressure

Upward

Movement

19. Synthesize A perfect flower has both male and female parts. An imperfect flower has ei thel' male or female p
Performance Assessment Diagram a Plant

Draw and label a diagram that shows the major p
LESSON

1

This flamingo was born with some traits and it acquired others. What

determines traits?

Read about it in lesson 1.

LESSON

2

Certain traits

help organisms to survive. Why

are some traits more common

than others?

Read about them in Lesson 2.

How Are Traits Inherited? Why It Matters ... A trait is a physical or behavioral characterist ic of an organism. Every person has a unique combination of tra its. You have a set of traits

that belongs to you alone. Yo u also have traits yo u have acquired from interacting wit h your environment.

PREPARE TO INVESTIGATE

Inquiry Skill Analyze Data When you

analyze data, you look for patterns in information you have (ollected.

Materials • index cards • pencils

Science and Math Toolbox For step 3, review Making a Chart to Organize Data on page H11.

Trait Tabulation Procedure

o o

Collaborate Work in a small group. Your

team will get a tetter. Assign a number to each person in your group. for e~ample. your group letter might be C and your number might be 5, or C5.

Observe Copy th e chart shown at right onto an indel<. card. Write your numberletter code, not your name, on your card.

Answer the questions in the chart.

e Collaborate Collect your team's cards and exchange them with the cards from
o

trait. Work in the same way with each of the other teams. Record Data Tally the results for everyone in the class. Prepare a circle graph. bar graph. or appropriate chart of your choice to show the dClta.

Conclusion 1.

Use Numbers How did the data change as you counted more people in the class? Why is it important that scientists use a large number of samples when doing research, such as you did in th is activity?

2.

Evaluate Of the five traits you studied, which could change as a person grows older? Which always stay the same?

3.

Analyze Data For each trait, which form did you find to be the most common?

II

Design an Experiment With your tea(~r's permission, survey students in other classes about the five traits. Is the additional data consisten t with the data from your d(lss? What conclusions (an you draw from your results?

v afn by Reading VOCABULARY acquired trait

chromosome

'"

gene

heredity mutation

nucleotide

.... .....'"

Traits MAIN IDEA living things inherit many t';,Iits from their

parents. They acquire others from tlleir environment.

.", .", p,11B7

Traits of Organisms

p,A81

tend to look like their parents and grandparents because of heredi ty. Heredity is the process through which trails are passed f["Qm parents to offspring. Humnn trai ts that are pnssed by hcredity-or

READING SKILL Sequence Use a chart like the one below to show the ordl'f of events in DNA

replication.

DOD

Do you look li ke anyone in you r family? People

inherited traits-include face shape, hair color, and blood type. The color of an animal's fur, the shape of its ears, and the arrangement of its teeth are also examples of inherited trails. The colors of a flower o r the shape of a fruit are examples among plants. An inheri ted trait Gill also be a behavior, such as the way a spider spins a web. Not every trait that you can observe is passed down by heredity. Some trai ts are acquired. An acquired trait is one tha t an organism develops after it is born. Some acquired trai ts come from the environment, o thers arc learned, and s till others arc brought about purposely.

Acquired Traits Flamingos are known for their beautiful pink color, which sets them apart from other large, long-legged water birds. The color comes from pigments in shrimp and certain algae that flamingos eat. The pink color of flamingos is an example of an acquired trait. This kind of trait comes from in teractions with the environment. In a similar way, organisms can acquire traits from food, soil, water, and other elements in their environment. Some acquired traits are learned. You were not born knowing how to ride a bicycle or a skateboard-y," learned how to ride. All types of animals learn behaviors. Dogs can learn to follow commands, lions can learn to hunt, and birds can learn how to sing songs. An acquired trait of this kind is called a learned trait. Manipulated traits are traits that people deliberately change. Plants and animals have been manipulated for thousands of years. Breeders mate animals or cross plants with the most desirable traits. Gardeners also control the shape and design of a plant to keep some plants small or to give others interesting shapes. Some traits arise from combinations of inherited and acquired featuTCS. For example, a person may inherit the capadty to be tall. However, the trait will show itself only if combined with proper nutrition and exercise. How migh t a plant develop an acq uired trai t]

Learned ... Organisms can acquire traits, like the ability to ride a skateboard, by learning and remembering skills and information.

Environmental ... Organisms (an acquire traits from their environments. A flamingo is pink because it eats pink 1000.

Manipulated ... Manipulated trai ts, such as coiled bamboo, are created by human design. People '-In change both inherited and acquired traits.

Chromosomes and Genes What determines the inherited tr
As the cell gets ready to divide, however, the double strands of DNA coil tightl)'. These shorter, thicker coils of DNA form rod-shaped structures called chromosomes. Chromosomes are visible under a microscope. As a cell is dividing, each chromosome consists of two identical h
Cells and DNA Organism In the (ell~ of a human, an onion plant, or any organism, a molecule called DNA con trols all cell activity. ~

Cell ... Just before the cell divides.. in DNA (oi ls tightly in to rod·shaped chromosomes.. • Lesson 1

In every plant and animal, one type of cdl is made with only half the chromosomes of other cells. These are the cells used for reproduction. They are called gametes, or egg and sperm cells. Human gametes, for example, contain only 23 chromosomes. When two gametes combine, their chromosomes bc
The Structure of DNA The basic units of DNA are called nud eotides. E.1ch nucleotide is made up of a phosphate, a sugar, and a nitrogen base. There arc four possible nitrogen bases. Recall that a molecule of DNA resembles a ladder. The phosphate groups and sugar molecules make up the sides of the ladder. Pairs of nitrogen bases make up the steps. Pairs form only between specific bases. The order of the nitrogen bases determines the genes of the organism. Because the bases can be arra nged in a great number of ways, a great number of genes arc possible.

~liJ,]l!M'

Why do body cells have twice as many chromosomes as gametes?

Chromosome ..

DNA ..

A chromosome is made of two iden tical strands, called chromatids. joined at th e centromere. The DNA is organized into units called genes..

The information in DNA ;s coded by its arrangement of nitrogen bases. A single DNA molecule may have billions of base pairs!

A87

DNA Replication

During replication, a DNA molecule separates. Each strand is used to form a new DNA molecule. A

The two new molecules are identical to the original. A

DNA Replication

Protein Synthesis

Before a cell divides, an exact copy of its DNA is made. This process is called DNA replication. To begin the process, the str~nds of the DNA molecule sepa rate along their nitrogen bases. This part of the process resembles unzipping a zIpper. Quickly after, bases floa ting around the nucleus attach to the bases of unzipped strands of DNA. Remember that bases always pair up in the same combinations. T hat means that the same type of base that just separated from one strand attaches to take its place. This process happens to both of the unzipped strands. When all the bases are in place, a new strand has formed on each of the original strands. In this way, two new DNA molecules are formed, each identical to the original.

What is so important about the order of bases in the DNA molecute? DNA directs the production of substances catted proteins. Proteins control most of the life processes in cells. They are also necessary for building and maintaining cells. It is the proteins that cause certain traits to be expressed in an organism. Proteins are made up of smaller units known as amino acids. There are 20 different amino acids that can be arranged in many different combinations. The specific arrangement of amino acids determines the na ture of the protein. Recall from Chapter I that proteins are formed on cell organelles called ribosomes. By means of intermediate molecules, DNA directs the order in which amino acids are arranged to form these proteins. Through this action, DNA controls all cell activities!

ASS • Chapter 3 • Lesson 1

Mutations

Can you find the mutation?

Mutations Occasionally, an error occurs during the process of DNA replication. This kind of change is called a mutation. A mu tation may cause a change in the proteins formed in a cell. Many mutations arc harmful because they decrease an organism·s chances tor survival. In rare cases, mu tations are hel pful because they resul t in desirable trai ts. Some mu tations are neithe r ha rmful nor helpful. Even if they result in changes to the organism's proteins, the changes are less obvious and do not directly affect the survival of the organism. Ma ny mutations occur by chance. Other mutntions are caused by environmen tal factors called mu tagens. Ultraviolet radiation from the Sun and «,rt.lin chemicals, such as some pestiddes, can act as mutagens.

Can a mu tation be passed to an organism's offspring? This depends on the «,II in which the mu tation occurs. If the muta tion affects a gamete-a sperm «,11 or an egg cell-the mu tation may be passed on to the next generation. Mutations tha t affect body cells only:lrc no t p:l55Cd nlons.

~iU 11!l:1!i

How does a

mutation affect the traits of an organism?

Do you see the different streaks and

colors on the (orn kernels? They Cilme from mutations---(hanges to the normal replication of genes. ...

Genes and Health Some human di seases Me inherited because they result from mutations in one or more genes. Sickle cell anemia is a disorder that results when a person inherits a mutated gene for the production of hemoglobin. In blood, hemoglobin is the protein that carries oxygen. In this disorder, one of the nitrogen bases in the gene for hemoglobin is changed. This error results in the production of protein that causes red blood cells to be shaped like sickles instead of the normal donut shape. The sickle shape prevents the cells from working properly. Cystic fibrosis is another inherited disorder. This is a disease that results from genes that produce a defect

in proteins that con trol the flow of certain materials inlo and out of cells. Some other inherited diseases include hemophilia and muscular dystrophy. Hemophilia is a disease in which the blood does not clot properly. Muscular dystrophy causes the muscles to break down over time. Another type of genetic disorder occurs when chromosomes do not separ.lte properly during reproduction. Recall that ch romosomes are copied before a cell divides. The copies split apart, and one copy goes to each new cel~. Oo\\,.n syndrome occurs when a specific pair of chromosomes does not separate properly. The extra chromosome results in physical problems and some mental retarda tion.

~ 'jHI!l:!j.

How does sickle

c~ll anemia

.. ff~cl human he .. lth1

CrUM:

-

~mucus~'

lilHosls

(Ioggir.g longs and d~'iw "~ad.

Hemophilia

Pr~ts body" from producing doI1lng factors, rtwitir.g in onoonlr<)llf(/ blefdirlg.

MOS
Prevents body" from mating pr~ lor rouS
riy5trophy

........... Crfat~

rf(/ bIorxI ctlh shiIpfd like Skt1t ctlls bIod; odltf (.ts in tht bIoodstrtanl and (\0 not any f i much GrY9M.

~

Ago • Chapt er 3 • Lesson 1

Sickle (ell anemia produ-ces blood (ells in an abnormal sickle shape. Sickle celb block other blood (elil. T

Review

o MAIN IDEA What material Trilits (an ~ i nh~ r it~ d from parents or a(quir~d from the environment

carries the information that determines genetic tra its?

a VOCABULARY Write a

sentence or short paragraph using the terms gerJ('s and DNA.

f) READING SKill..: Sequence DNA in (hromosomes contains genes that determine the traits of an organism.

What steps take place durillQ DNA replication?

o CRITICAL THINKING: Apply How do mutations affect an organism? Why can some mutations have no effect?

Mutations oxcur when the bases in a genetic sequence change.

o INQUIRY SKILL: Analyze Data

.e MATH

What in/()(mation would a scientist need to discover whether a disorder had a genetic cause. an environmental cause, or a combination of the two?

TEST PREP Human traits are most accurately described as

Make a Bar Graph Research the number of chromosome pairs in fi~e different species. Create a bar graph that compares them. Does the number of chromosomes per celi relate to the complexity of the organism? Draw a conclusion from your data.

B. both inherited and acquired.

TECHNOLOGY

D. like those of plants.

Write a Do(Umentary Scientists continue to de~elop new technology to study and manipula te DNA. Research the Human Genome Project. genetic engineering, or other scientific advances. Presen t your findings in the style of a television documentary.

A. almost entirely genetic in origin.

C. almost entirely learned Irom other humans.

Technology Visit www.eduptacuomlscp llQfiod out more about herl'd<\)'.

A9I

•

dFranklin

(1920-1958)

In 1962, James Watson, Francis Crick, and Maurice Wilkins were awarded the Nobel Prize for discovering the structure of DNA. Yet their achievement I"\'lied greatly on it WOlTh1n who was not so honored. Alas, Rosalind Franklin hild died four years earlier. As 11 you ng girl, Franklin was energetic and talk.1Iive, often arguing politics with her father. She excelled in school, especially at science. She became the fi rst woman in her family to gr.lduate from (;olll'ge with a science degree. Her mos t famous works are her x-ray pictures of DNA, such as the one shown here. Other scientists

had tried to t"ke pictures like thi s. However, Franklin recognized that DNA changed its shape in water. She ca refully and precisely added just the right amount of water to her specimens. From her pictu res and other data, she determined much about the shape and composition of the DNA molecule. One of Franklin's colleagues described her with Miss Franklin was distinguished these words: by extreme clarity and perfection in everything she undertook. Her photographs are among the most beautiful of any substances ever t
Compare Franklin's X·ray picture to tile illustration of DNA on page A81 . ...

~2 • o...pte. 1 • le-sson 2

)

------U

READING

Lynn Margulis (1938-

)

In the 198Ds, scientists studying cells discovered something they did not expect. Mitochondrin, the cell pMts that produce energy, have their own DNA! This DNA conlmls only the mi tochondria. [t works apart from the DNA in the nucleus. Yet, the discovery did nol surprise everyone. Years earlier, biologist Lynn Margulis predicted just such a finding. The prediction was pari of a larger idea she proposed about cell

history. It is Cill!ed the endosymbiont hypothesis. According to this hypothesis, mitochondria and chloroplasts were once smilll, free·living cells, much like bacteria. At some point, a larger, amoeba~1ike cell engulfed some of them. Yet, instead of breaking apart, the small cells stayed alive inside the larger cell. After mnny cycles of reproduction, they became cell parts. The endosymbiont hypothesis explains much about mi tochondria. As for Margulis, she now is recognized as an insightful and dedicated scientist. Animal Cell Unique features of mitochondria • Able to use oxygen • Surrounded by a double membrane • Divides separately from the rest of th e cell • Kas its own DNA that resembles bacterial DNA Nudeu~

Sharing I. READING (HE(K What did Frankl in and Margulis show about DNA?

2. WRITE ABOUT IT What does Margulis' hypothesis explain about cells?

l TAlK ABOUT IT Which science skillS did Ffanklin and Margulis pradice?

Why Are Some Traits Very Common? Why It Matters ...

PREPARE TO INVESTlGATE

For a species to cont inue, its members must reproduce. Sometimes, new individuals are exact copies of one parent. Other times, they

Inquiry Skill

are similar to two paren ts, but not

exactly like them. When the two young giraffes become adults, they """"' ~ traits to young

thei r own.

Use Models When you use models. you make an object that helps you understand a concept or process.

Materials • 4 each of 3 shapes of beads or buttons, with e.w. I I I)

in

Science and Math Toolbox fof step 2, review Making a Chart to Organize Data on pagt H11 .

Chromosome Combinations Procedure

o

Use Models Model genes on chromosomes by stringing three beads on each chenille stem. Refer to the chart to find the meaning of each type of bead. Thread the

,

-0 e - r.... lt

'"

~"

~

"',

~.

I

,

--0 -

"-I

ear shape gene first, t hen the eye color

gene, and then the gene for hair color.

e e

Separate the chromosomes into two pairs to represent two parents. Record Data In your Science Notebook, dra w the bead shapes and colors on the chromosomes for each parent. Create a chart to organize your data.

Experiment Take one chromosome from the first parent to form a gamete chromosome. Repeat for the second

parent. Draw the gamete chromosomes in the chart. Then combine them to form the chromosomes for a new cell called a zygote. Draw the ch romosomes of the zygote in the chart.

Conclusion 1.

2.

Analyze Data Is it possible to predict the offspring's chances of having a certain hair color, eye color, and ear shape? Why or why not?

Design an Experiment

Use Models Make a model of two parents whose traits are exactly alike and model the offspring's chromosomes. Are the traits

Find O!Jt what happens when you add more choicl?S of trailS.

of this offspring more predictable than

those of the f irst offspring you modeled?

'.

Make models with several choices for f!je color, hair color. and one other trait.

VOCABULARY adaptation asexual reproduction dominant hybrid recessive seledive breeding sexual reproduction

p.
.'"

READING SKILL Cause and Effect Use a (hart IiI:!:' the one below to

show the effects of selective breeding.

DO DO

How Traits Are Passed MAIN IDEA Over many generations. species develop traits that help them to survive.

Asexual Reproduction You learned in Chapter 1 that some organisms need only one pMcn t to reproduce. In asexual reproduction, offspring are produced from one parent. B.1cteria and many protists typically reproduce asexunlly. Re(:all tha t fission and budding are the simplest types of asexual reproduction. Spore forma tion, which you read about in Chapter 2, is another kind of asexual reprod uction. Yeast, for example, may produce spores that are spread by water and wind. Ench spore cnn grow into n new yensl orgnnism. When nn organism reproduces nsexunlly, an exact copy of DNA is passed from parent to offspring. Generation after generation, the offspring hnve the same genetic material, or DNA. Mutations are the only sources of new traits in this type of reproduction. Plant lets are offspring that break off or are cut away from the parent plant. Each plantlet can become a separate plant wi thout fertilization. 'Y

Regeneration Star/ish, or su stars, u n grow n~w arms to r~l'lac~ thos~ that hav~ b~~n cut off. This r~g~n~ration is a form of as~ . .. al r~prod .. ction.

In the simplest organisms, such as bacteria, most or all reproduction is asexual. Other organisms use asexual reproduction part of the time. Many fungi and plants, for example, alternate between asexual reproduction and sexual reproduction. Yeast also alternate. A yeast produces buds asexually. The bud brea ks off from the yeast cell and begins to grow. At other times, the yeast produces male and female gametes. These cells can combine to make a new yeast cell. Plants have several different asexual structures. Some plants produce long stems or roots that then grow plantlets, or baby plan ts, that break off from the parent. Other kinds of plan ts can grow from root cuttings or from stem fragments. Budding Hydra are animals that rep roduce asexually by bu dding. They can also reproduce using female and ma le game tes. ~

Another asexua l process in some animals is regeneration. For example, flatworms called plallaria can rcgcncr;>tc. If ;> pl,In"'i" is cu t in h;>lf, each half will grow to produce two whole worms. Cells divide during both asexual reproduction and regeneration. In both processes, the new cells have exactly the same DNA as the original cells. Replicating and passing on the same DNA helps ensure tha t traits will stay the S<1me.

!) UU~I AND IfHCT

How many parent ce lts are needed for asexua l ' eprod uction7

Sexual Reproduction SeKuaJ reprodu ction occurs when a female gamete joins with a male gamete to form a new organism. In addition to yeast and algae, animals and plants also pr~ctice scKual reproduction. A flowering plant has male and female reproductive structures in its flowers. Pollination occurs when pollen is transferred from the male part, a stamen, to the female part, a pistil. A sperm cell released by the pollen then fertilizes an egg cell. In Lesson 1, you learned that gametes contain half the number of chromosomes as in the organism's other cells. When a sperm cell

Pollen contains mate sea cells that have the male genes.

combines with an egg cell, the chromosomes become part of the same cell. The result is a cell with a complete set of chromosomes. In this way, the offspring Tc.:eives one chromosome in each pair from each parent. Each chromosome contains genes that determine the traits of the offspring. The offspring receives two genes for each trait. Different genes may code for different forms of the s.1me trait. For example, suppose a bee carries pollen from a red flower to a yellow flower. The offspring may receive a gene for red flower color and a gene for yellow flower color. Red and yellow are two forms of the same traitflower color.

A bee Of other pollinatof lfanspollS male genetic material from flower to flower.

egg is loca ted deep in the flower. The bee brushes the pollen on to the female pam as it looks for n«tar,

1ne form of a trait Ihal is expressed depends on the charaCI~iSlics of the genes. Some forms of a Irait are dominant and others are recessive. If an offspring receives genes for two diff('rcnt forms of a trait, the trai t of the dominant gene is ex pressed. The recessive gene is not expressed. Suppose red flowers are dominant for a particular plant. An offspring plant that receives a gene for red flowers from each parent will ha\'e red flowers. So will an offspring plant that receives a gene for red flowers from one parent and a gene for yellow flowers from the othCT parent. The dominant trait is expressed instead of the re<:cssive trait. Only offspring that re<:eive a gene for yellow flowers from each ~..,rent will have yellow flowers.

....

An org.1.nism that has two identical genes for a trait is Solid to be purebred. A purebred org.1nism can have two dominant genes or two re<:cssive genes. An organism that ha s two diff('ren t genes for the same trait is called a hybrid. The offsp ring of hybrids may express traits that are different from eitncr p.1rent. Think again about the red and yellow flowers. Suppose a bee carries pollen from a red flower to a red flower. Because red flowers are dominant, you might think that all of the offspring will have red flowers. If the parents are hybrids, however, they each carry a gene for yellow f1owers-t'ven though you don ' t see it. If an offspring happens to re<:eive a gene for yellow flowers from each parcn!, It wtll CXpTt.'SS the n'C~:'s~lvc trait of yellow flowers.

~ CAUSE AND UfEO

tn

se~UilI

reprodtKtlon, how many cells uea te a new organism ?

The 'ertilizHi fogg conl,lins

__-.J

DNA 'rom bolh paren .--_~

flowers embryos, Or fir51 (elis, of the n!'X1 generation. Their

DNA comes from

display the trails of their spe
Bruss~ls

sprouts

Ancestral Plant? Broccoli, cauli flower, and Brussels sp routs are just a lew 01 t he variants deri~ by selective breeding from an ancient cabbage plant.

Selective Breeding For thousands of years, humans h,we identified and worked to il1Cl'Case desirable traits in plan ts and animals. Long before scientists knew about chromosomes and genes, farmers and shepherds were breeding plants and animals to obtain offspring with useful trai ts. The practice of breeding plants and animals for desirable traits is known as selective breeding. Through selective breeding.. humans try to plan the arrangement of genes in offspring without actually changing the genetic material in any way. One method of selective breeding involves combining parents with two A100 •

l esson 2

or more different trails. This method is known as hybridiz,ltion. TIle go.11 of hybridiz,ltion is 10 produce a hybrid organism with the best traits from both parents. For example, a plant breeder might cross a rose planlthal produces large, fragrant nowers with a rose bush thai does not have thorns. The desired result would be a plant that produces large, fragrant flowers and does not have thorns. Selective breeding may produce plants and animals that survive specific environments. For example, red winter wheat is a hybrid that grows in cold weather. It allows fanners to harvest two whea t crops a year, even in cold clim,ltes.

Another method of selec tive breeding invoh'es combining plants and animals with the S
Why do you think people breed thornless roses? .. Today. farmers and ranchers use technology to impro\'c crops and animals. For example, food additives can stimulate hens to 1..1Y more eggs or cows to make more mi lk. Some crop plants release compounds that kill insect pests. Also, computers make it easier to document selective breeding procedures and to identify pMtcms in the results. (.lust lND HFECT

v.mt is the intended

result of selediwe breeding?

Some cows are bred to produce beef. Others art bred to produce milk.

Adaptations In nature, favOT
flowers. A parrot's be3k is short and thick, which leis i t crack open seeds. Other adaptations help orgilnisms defend themselves. Spines or stinging rays keep predators away or wound those that get too close. Thorns, spines, or tough leaves protect plants from being eaten.

'" AI. bladd~1l k~~p this seaweed fl~ tjng. lening its tuves bMIc in the Sun.

'" I'or
Ca mo uflage

Wa rning coloration

Mimicry

The walking slick is an insect that looks like a twig. It is well hidden.

The red and yellow pattern of the poison arrow frog signal predators that it is to~ic.

The king snake gets e~tra protection from looking like a coral snake.

Ca mouflage Many adaptations protect organisms from predators. The ability II) bl.,,,d i,,11) lit., ~unl)u"di"g~ i~ known as camouflage. Organisms wilh camouflage can hide from predators. For example, some inse.:ts look \'ery much like the flowers of their favorite plants. ~ typically gather honey at the times of day when shadows are deepest. Their black stripes blend into the shadows. Wa rning Coloration Bright colors often indicate that an organism is poisonous. The colors warn predators to stay away. The bright colors of many frogs warn other organisms thallhe frogs are poisonous. A predator that cats one poisonous frog is not likely to cat any others! Did you know that man)' birds avoid eating red inse.:ts? Red insects often are poisonous.

Mi micry The ability to look like another species is known as mimicry. All I)'g,"ri~m miglrl mimiL 'Ull)th." species th at is more threaten ing to a predator. The kin g snake, for example, is not a poisonous snake. However, it mimics the poisonous cor,11 snake, which most predators will avoid. Sometimes two species ha\'e adaptations that work together. Butterflies, for example, are attracted to plants tha t have man)' flowers in large clusters. The butterflies can eat nectar without using too much energy fly ing from flower to flower. In return, the butterflies help the plants by transferring pollen from one flower to anolher.

~ UUS£ AND EffECT What is a n a dapta t ion?

A10)

Review

o MAIN IDEA What process do huma~

Organisms reproduce in one of two main ways: Muua lly with only one parent Of se ~ ually wi th two parents.

use '0 influence the traits

of a species?

o VOCABULARY Write a sentence

or short paragraph using the lefms aSl'lIwl and adapt4licn.

o READING SKilL: cause and Through selective breeding. people crute offspring that have desirable traits.

Effect What are IWO possible effects that changes in envirorment can have on a s.pe
o CRITICAL THINKING:

Synthesile Compaie the benefits and ~awbads of asexual reproduction and sexual

Ad~pt"tions

help individuals to survive in their environments.

""""""'"

o INQUIRY SKilL: Use a Model How could you cr~t." model

to show the passing down of a recessive trait through three

geflefations7

~TEST PREP An Cldaptation is best described

MATH Makt,,(hart

A. a series 01 learned or acquired traits.

R~af(han

endangered species, such as t!'le bald eagle Of Florida panther. Make a chart that shows t!'le knoWfl population of the species at different times over the last SO years.

B. the result of e~perimentation by humans. C. a trait that is favorable to survival.

WRITING

Explanatory Research the history of horses in t!'le United States. Find out when hOfSeS arrived, how they were used, and how people have (hanged horses. Write a report to show what you learned.

D. an ane-mpt to

grow stronger

than other OI"ganisms. ~

ill

""04 ' Chapter 3 ' lesson 2

as

Technology V~it www.e duplace.comlK pitofind out mort about ~tions.

Chef Chefs prepare all kinds of creative and

tasty d ishes for restaurants , They also work at schools, office buildings, and other places that

serve food. Chefs must have excellent cooking Skills. Because foods come from living things,

chefs need to know the nutritional value of different plants, animals, and fungi. They also need to know how to makE' d ifferent foods look appealing and taste delicious. What It Takes!

• A certificate from a cooking school or training on the job

• Keen senses of taste and smell • An artistic flair. to prepare attractive dishes

Botanist Botany is the scientific st udy of plants. Bot anists may work to develop heartier crops or cures for plant diseases. Or they may resea rch new drugs from planH of the rain forest . Some botanists trave l the wo rld t o study unusual plants. Others work in laboratories, conducting experiments on plant parts and plant cells. Still others work with

far mers, dieticians, lands,app,:;,~~~:;;;::" or other people who work v What It Takes! • A degree in botany, biology, or ecology • An interest in plants • An appreciation for na ture

TRE",,,

, ...

\\

I \ J

\

This breed 01 Polish thkken lias been

,aiseil 101 at least SOO years. Today people raise fancy thkkens like these for fun, pro/it, and competition.

This hen is the offspring of a Polish

rooster and an Arautana f.iule hen. She got her lufte<.!

he~d

from Dad

and her fluffed-up body feilthe,s from Mom.

READING

: Compare and Contrast

Chapter

3

Review and Test Prep

Vocabulary Complete each sentence with a term fro m th e list. 1. A tra it developed through learning is a(n) _

.

2. A chemical sequence of DNA, or ~ determines a trait 01 an organism. 3. A(n) __ is made of a phosphate, a sugar, and a base.

4. The reproductive material known as __ appears in two strands coiled around each other. S. A(n) __ is a change in the arrangement of bases in a gene.

6. Bacteria multiply by _

7. A_

trait is expressed even if only one gene IOf that form of

the trait is inherited. 8. A(n) __ trait is only expressed jf an organism has two genes

for that form of the trait. 9.

practICe __ when they male organisms With ooirable traits. ~armers

acquired trait A84 adaptation AI 02 asexual re production A96 chromosome A86 DNA A86 dominant A99 gene A87 heredity A84 hybrid A99 mutation AS9 nucleotide AS7 recessive A99 selective breeding AI 00 sexual reproduction A98

10. Any trait that helps an individual to survive in its environment isa(n) _

' Test Prep Write the letter of the best an swer choice. 11 . Both traits from the environment and learned traits are _ A. passed down through the chromosolTlO?S B. ta...ght by parO?!1ts to offspriog C. always the re<;u~ of human intervention O. acquired by individua ls in each ge!leration

12. In Ofganisms that reproduce sexually. the number of chromosomes in body cells i, __ the number in gametes. A.ooe-half B. ooe-third A108· Chapter ]

C. twice O. four time-s

1]. In asexual reproduct ion. _

A. nucleotide-s join to form gene-s B. the olfs.pri"9 has exactly the S
breedi"9 B. introduc i"9 new predatoo or prey C. chaoging the environment O. all of the above A.

selecti~

Inquiry Skills 15. Ana lyze Data Copy or trace the diagram below. Choose labels from the list below to label the parts of the diagram. chromosome nitrogenous bas es ce ntromere

DNA gene

17. Synthesize Explain why it is nKessary in se~ ual reproduction for the gametes to have half the number of chromosomes found in body cells. 18. Apply Botanists and farmers save seeds in a seed bank. Explain the purpose of a seed bank. How can two seeds from the same plant ~ies be different? 19. Synthesize Explain why asexual processes are important to organisms that reproduce from two pilrents. 20. Apply list th ree inherited or acquired traits that help you survive. and explain why each tra it is an advantage.

Performance Assessment Describe Selective Breeding 16. Use a Model Draw a diagram that traces one pe.-son·s chromosomes back through at least th ree generations (parents. graooparents. and great·grandparents).

Use beads and chEflilie stelllS to model the process of selective breeding. Describe how gene numbers change from generation to generation.

Map the Concept Draw a Venn diagram like the one shown here. Write each term listed below in the space fO!' asexual reproduction. sexual reproduction. O!' both. budding DNA fertiliza tion mutations

one parent pollination regeneration two parents

Asexual

Sexual

reproduction

reproduction

Write the fetter of th e beu answer choice. 1. Which shows the mature ovary of an

angiosperm?

l . Water and nutrients!fom soil now to

the leaves of a vascular plant through A. ptJloem. 8. ij)Ofes. C. stomatil. D. K)1em. 4. The "master molecules" that determine

A.

an OI'ganism's traits are calledl ___ A. amino acids.

8. chromatids. C. DNA. B. ' - /

D.

genes.

5. Which is NOT a trait that this girl probably

inherited from her parents?

c.

D. 2. Which Ofgar.elle directs the activities 01a cell1 A. hairstyle A. "'''''''''' 8. Golgi appdfatr.rs

C. lysosome D. nucleus

( All 0

o

uniIA)

8. C.

~

color

nose me

D. mouth shape

5. 'Mlkh organ system indude5 the thyroid gland, ~enal glands. and pancreas? A. nefVOOS system B. excretory system C. endocrine system D. circulatory system 1. Which is NOT used during photosynthesis

to make food? A. B. C. O.

carllon dioxide

sugar sunlight water

a. Which OIyanism belongs to the fungi killQdom?

•

A.

c.

D.

•

•

~.~ . •

=

Answer the following in complete sent ences. 9. Name two di!oeases caused by single-celled

OIganisms. Explain 00w each disease makes people sick. 10. Some traits help animals to survive. Name a trait you have tha t helps you SUI'INe. Explain how this trait benefits you.

Everything the cell takes in and lets out must pass through the (ell membrane. Cells may grow larger as they re(eive food and oKygen. The larger the (ell grows, however, the more nutrients it needs to stay healthy. Beyond a (ertain (ell siz e, the (ell membrane (annot take in nutrients qukkly enough.

You ran {Ompare a cell to

a SIl9
If tfle sugar cube doubles in widtll, the ratio of SIlrface area to volume decreases to 3 to 1.11 a cell grew like this. food arK! oxygen could not diffuse qu ickly enDll9h for til e cell to survi~.

Instead of g,oy;ir>g larger and large.', cells divide imo new cells. To survive. h(lW(!ver, eadl new cell must continue to borde!- a supply of food and oxygen.

I

•• .J ".

VOIu~:

t , ... '

Surface Area: 6 em'

VDI_: 8 un' S<Jrf",. Ar." 24 un'

Vohne; 2 un'

Surface Aru: 12 em'

In al l living thir>gs. cell size is limited by the ratio of surf
Interactions Among Living Things Chapter 4

Ecosystems. Communities, and Biomes .............. 82 Chapter 5

life in Ecosystems ............................................ 834

_ _ Independent Reading _ _

Life on the

seumgeti

Biomes

Father Eusebio Francisco Kino

The ea rs of a jackrabbit measure one-third t he length of its body! How do long ea rs help a jackrabbit su rvive in hot places? In th is unit. you'll learn how certain characteristics help anima ls survive in their native habitats.

LESSON

1

Sunlight, water, air, plants, animals, and you- how do you and

other living things interact with the environment? Read about it in lesson 1.

LESSON

2

Lots of rain or plenty of sunshine-in which type of biome do you live? Read about it in lesson 2.

Producers, consumers, decomposers- '.n you find your way

around a food web?

Read about it in lesson 3.

How Do Living Things Form Communities? Why It Matters ... You 'ive in a community made up of trees and grasses, pets and people,

and all tile other living things in your area. Living things interact with one another and with nonliYing things. In nature, everything an animal needs to survive-including food, air, and

shelter--
PREPARE TO INVESTIGATE

Inquiry Skill Observe When you observe, you use your senses to determine and describe the

properties of objects and

events.

Materials • :.<.Iii

• 500 ml Ileaker • teJlarium

• water • earthworms

• organic maller, such as peal moss or decayed leaves

Look at Life Procedure Safety: Wash your hands after setting up the terrarium.

€I Collaborate

Work in a small group.

Measure 500 ml of soil in the beaker. Pour the soil into the terrarium. Spread a t hin layer of organic matter over the soil. Add earthworms and a handful of food scraps,

e

such as apple peels, to the terrarium.

1~ ...... rlym

lIVI""

ECO
no",," !'Io.'. . .1 no''''"

Predid Add water to one side of the terrarium until the soil is slightly wet. In your Science Notebook, predict how

the earthworms will react to the water.

e

Loosely place the lid on the terrarium. Place it out of the sunlight. Classify Make a (hart in your Science Notebook like the one shown. Classify

the things in the terrarium as living or nonliving.

<)

Observe Each day for one week, carefully

observe the earthworms and their environment . . , Record Data Write down your observations in your Science Notebook, Indude the time and day of each observation.

Conclusion 1.

Observe What interactions did you observe between the earthworms and their environment?

2.

Infer Based on your observations, what do earthworms need to survive?

Inve'Stigate More! Design an Experiment Predict whether eanhwl)lms grow largest in fine, coarse. or rocky soil. How could you test your prediction? Run an exptfiment with your teacher's approval.

v

atll by

Reading

VOCABULARY (ommu nity

ecosystem pOpu lation

.

p. 87 ~

pl,ml s .md a nimals, as well il S t he waler, soi l, a nd other nonlivi ng thi ngs in the ilrea .

,~

READING SKill Main Idea and Details As yoo read. write down deta ils that des<:ribe

ecosystems.

MAIN IDEA An ecosystem is a commun ity of different

What Is an Ecosystem? If yOll put your head on the ground of a forest, what would you sec? You might notice ants marching in line, or worms burrowing through the soil. Fuzzy mosses might tickle your nose, and twigs and bits of leaves might stick in your hilir. A section of forest floor is one example of an ecosystem. An ecosyste m is made up of all the living

and nonliving things that interact in one place. [n a forest, the living things range from tiny bacteria find earthwonns to t~ towering ilbove. Nonliving things include sunlight, soil, water, a nd air. Scientists define and study smnll ecosystems, such as a rotting log or a pnlch of soil under a tree. They nlso study lnrge ecosystems, such as a large forest or prairie. Regardless of size, everything in nn ecosystem in terncts.

Small Ecosystems Soil, a rotting log, fungu~ moss, and a lizald are all part

01 this small ecosyste m.

The Florida Everglades is " large ecosystem in southern Florida. The land is swam py, co\'ercd by a thin layer of muddy water. Grasses grow tall because only a few cypress trees block the sunlight. Closer to the ocean, salt water mixes wi th fresh watcr in shallow lands callcel est uaries. Mangrove trees thrive in estuaries, as do newly hatchcel fish and shrimp. Many birds ncst in the mangroves and fish the waters for food. 1ne plants, birds, fish, and other organisms of the Everglades make up a community. A community is the group of living things found in an ecosystem. These living things depend upon one another for food, shcl ter, and other needs. They also depend upon the nUll living things in thc ecosystem.

Organisms tha t live well in one ecosystcm might not survive in another. Alliga tors, for example, find food and shelter only in warm, wet places. They also must drink lots of water to fl ush wastes from their blood. Li ke the alliga tor, the roseate spoonbill is well suited for life in the Everglades. Its tall legs and strong feet are ideal for wading. [t shakes its open bill through the water to captu re small fish and other animals.

i! i j

Oescribe some interaction s ilmong living th ings in the Everglades.

Large Ecosystem The F[orida Evtrglldts includes a communi ty 01 many living thing$, induding cyprts$, bird$, panthtr$, and aliigltors.

Populations You CM! learn a great deal by stud ying an individual plant, animal, or other organism. But to understand how an ecosystem functions, )'ou need to study populations. A population consists of all the members of the same type of organism that live in an ecosystem. TIle Everglades e(osystcm includes populations of mangrove and c)'press trees, alli gators and spoonbills, and a wide variety of other species. TIle birth or death of one plant or animal is not likel)' to change the Everglades very much. But what if a disease killed all the mangrove trees? Or a new animal species began nesting where the spoonbills nest? E\'ents like these can affect the cnlLre commumty.

To evalua te ecosystems, scientists consider factors that affect the whole communit)'. One majorconcem for the Everglades is the water supply. lhe Everglades depends on fresh water flowing from the north. Yet human needs are draining that suppl)" and those needs are growing every yeM. In an ocean ecosystem, which fish wou ld you suspect are most important in the community? Arguabl)', the answer is the smallest fishes, including herring and mackerel. These fish are food for bigger fish, which in tum are food for sharks, killer whales, and other big animals. Without large numbers of small fish. many other animals would starve. Why are small fiU!

np,n,", in ocean ecosystems?

feeding Relationships Small fish nl algH lind other plant life. ;vwI they are food for larger fISh. fet-ding relationships like these ~re a pari of all ecosystem!..

Review

o MAIN IDEA How do §cientis\S classify the parts of an

£cosystems art made up of all tile living and nonliving things th,t In teract in a gi_

ecosystem?

6

VOCABULARY Use the terms ecosystem, communit): and pcpuldrion to describe the area where you live.

9

READING SKILL: Main Idea and Details What nonliving things are loond in ecosystems? Why are they important?

,,~.

A community is m.1de up 01 different p"pula ti"ns ollivi",!! things in an ecosystem.

o CRITICAL THINKING: Apply What might happen if one population in an ecosystem disappeilred? Give an example.

A poplliation (OfI$ists

01 all the m_btf$ 01 tile same type "I o'!p"ism that live in a community.

o INQUIRY SKILL: Observe

Go ootSlde With a partner and

carefully observe a small patch of grass. Classify the things you ~e as living or nonliving .

.,e TEST PREP MATH Make an Estimate

What ITlilkes up an ecosystem? A. plant and animals only

A stable

population of slll
TECHNOLOGY Maku Poster Use the Internet or library to uplore wtlich types of technology sdentists use to study ecosystems. Share your results with the class by making iI poster. Use words and images to explain how the technology works and IIow it is used.

B. water. air. and otller nonliving

things C. all the living and nonliving things and tlleir interactions D. one populiltion only ~ Technology

.iii.

Vi$it w_.edupt;w:uomlscpl to find out fflOft aboot f(OSYS~.

"

What Are Biomes? Why It Matters ...

PREPARE TO INVESTIGATE

Is your area usually hoi and wei, or (old and dry? Are there thick

forests or tall grasses? These types of factors affect many parts of your life, including the kind of home you live

in and the clothes that you wear.

All plants and animals afe affected by their environments. The prairie

dogs shown below live very well on

Inquiry Skill Analyze Data When you analyze data, you look for patterns in the information to make inferences, predictions, and other generalizations.

Materials • different-colored pencils

the grasslands. but would not survive on the tundra or in a rainforest.

• calculator

Earth 'S different regions support

Science and Math Toolbox

different kinds of living things.

For step I, review Making a line Graph on page H13.

rw ., , ,

,

Compare Climates Procedure

o

Use Numbers In your Science Notebook make a line graph using data in the temperature ch art for Des Moines, Iowa and Iquitos, Peru. Plot the months on the

x-axis and temperature on the y-axis. Use Numbers Use th e data in the precipitat ion chart to make a bar graph in your Science Notebook. Plot the

months on the x-axis and precipitation on the y-axis. Use Numbers Calculate average annual rates of

precipitation and temperature for both places.

D.o~

Moln ....

I,\u l~

•.

Jwe~.

Jan.

~

-n

~,

~,

~

~,

=

Mar.

,~.

" ~<

r.mpcrawre

"" n =

Jun.

Jul.

Aug.

'" u,

0<

=

"p.

0<,

"~.

,~

'"

n

= =

U<

~<

"".

4<

'" '"

A~"'e' f're<;Jpit.1ltion

... .. .. ..

Dee Mol" ...

'" '"" ". ". ,..

Iquito<>

u ..

Mar.

~

~

"'pr.

~

""

Jun.

... ... ,.. ... Jul.

~,.

11.m

\~

om

260m

\~

om 16 om ' 2 0"

"F

n ..

0<,

"~

".

,""..

19 om U . . 26.m

Conclusion 1.

2.

Analyze Data Describe temperature and precipitation patterns in both places. Whi ch place receives more precipitation? Is precipitation constant throughout the year?

CGmpare Use the data to compare Des Moines and Iquitos to your community.

Design an Experiment Study a globe to find a city of the same latitude as Des Moines. Ii 101" that city. How do their climates compa re? Make a chart or graph to show data.

v afn by Reading VOCABULARY

biome dimate desert

p. 81l p. Bl,

grasslands

p. 814

Biomes MAIN IDEA Biomes 'lre '3'ge regions of Earth. filch biome h
p. 81 4

taiga II- 81 S temperate forests p. BU tropical rain forests p. SH tundra p. SIS

READING SKILL Text Structure A<, YOU read,

use the heads and subheads

to outline the lesson.

Earth's Major Biomes A biome is a large group of ecosystems that have similar characteristics. Study the map below to find the six major land biomes. What makes biomes different from one anothe r? The most important factor is climate. Climate refers to the type of wellther that occurs in an area over a long period of lime. Some climates are rainy, while others are qui te dry. Some have a variety of temperatures, while others are almost always hot or cold. Different climates support different populations of living things. Earth is home to six major land biomes. In each biome, {limate affects the kinds of plants and animals that live there. T

World Biome5

4 • l esson 2

Forest Biomes Forests are home to tall trees and the animals that live in them. Forests are part of two biomes. Tropical rain forests are very rainy and hot. Some ra in forests get more than 600 em (240 in.) of rain each year! Tempera tures range from (lbout18°C to 35°C (64"F Q to 9S F), which is like a hot summe r that lasts (Ill ye(lr. Bec(luse of the moisture and warmth, tropica l r(lin forests arc tC
r.) TEXT STHUCTURE

Compare the climates 01 bo th fOreSis.

Location: near the equator Climate: Warm and wet

Temperate Forest Location:

e~stern

North

other pl~, ~s Climate: four distinct seasons Amerk~ ~nd

Grasslands and Deserts

distinct

Grasses cover the land in the grasslands biome. Trees are few and far between. There are two main types of grasslands: prairies and s<wannas. Prairies are found in temperate regions, such as the central United Slatcs. Temperatures may dip as low as - 40"C ( - 400F) in win ter and 50ilr to 38°C (100"F) in summer. Pra irie animals include prairie dogs, coyotes, hawks, and grouse. Most s.wa nnas are found in warmer regions, such as central Africa. Yearly temperatures typi cally remain above l80C (64°F). Elephants, gir.,ffes, lions, and zebras call the savanna home. A S
Taiga and Tundra The taiga biome has long, severe win ters and short, cool summers. Temperatures may reach lOoe (SO°F) during only one to three months e
~ 1!JjI3l;li !,!i!j!' How do temperatures compare in t he taiga and lundra?

nortllern North Amerit, ltIId Eurasi,

Climate: ~re wintelS and sIIo.t

Lo~tion :

I

~oot

neal tM

Marine Biomes Look back at the ma p on page B12. Oceans COVCl" about 70 percent of Ea rth 's surface! They art' home to the marine biomes. U ving things need special adapta ti ons to live on or ncar the ocean short'. This is because the wa ter le" el keeps changing wi th the tides. The intertidal zone is the arca that ocean tides co\·er and UTlCover in a regular cyde. Sometimes this zone is under water, and other times it is exposed to the Sun and air.

In this zone, an ima ls such as da ms and mussels attach sticky threads to roc ks so the waves won' t wash them away. Other an imolls, including many kinds of crabs and some snilils, can move about over land and und en,'ater. just beyond the shore is the ncar· shore ...one. In some pIOlC('S, this zone is home to an und erground forest of ta ll, brown seOlWeed called kelp. Otters and other animals li ve among the swaying stalks.

The presen(e of water and sunlight defines the zones of marine biomes. Different plants and animals li .... e in each. T

Intertidal Zone

•

stars. and Cfabs live in ttle (onstantiy (hanging (oOOitions of ttIe intertidal lOne.

Mussels. sta

-

fish and other marine lile live among the I.~ kelp plants in some nur-shofe zones.

Still farther out to sea is the open ocean zone. Here, the wa ter is deep and (old. Tiny algae floa t near the surface. Algae nre plan t-li ke organisms, and most are singlc-celled. Ik<::nuse nlgae nre so numerous, they produce most of Enr th's oxygen! They also provide food for ocean an imals. Even when the wn ter is clear, sunlight mostly reaches a depth of only nbout200 me ters (660 ft). So, the floor of the open ocean is very cold and dark. Organisms here usc spedal adnp tations to survive such n hnrsh environment. Some fish produce their ow n ligh t, just ns ligh tning bugs do on land. The light helps them to hun t for food.

Other unusual organisms include the giant tubeworms that live by vents on the ocean floor. These vents release heat nnd gnscs from Earth's interior. The tubeworms are unusual because the ven ts--not the Sun--.1re the source of their energy. Bacterin ncar the vents ma ke food using hented chemicnls, n process unli ke any other on Earth. ~ TElT STRUCTURE condition~

Compa re the in th e th ree ~one~ of t he ocean .

Dolphins. whales. and je llyfish spend much of the ir time near the surface in open ocean ~0 f>l'S.

Open Ocean lone

HUge ~chools of he rrin9, tuna, and other fish live in the middle depths of the open CKl'an.

Fa ngtooth fi sh and other crea tures have ada pted to the cold and darkness of the

Freshwater Ecosystems Other bodies of water are made up of fresh water. These ecosystems include streams, rivers, ponds, lakes, and wetlands. Streams and ri\'ers contain nowing water. Near the beginning of a river, the current is usually fast and the water is clear. Trout and other fastswimming fish H\'e in this lOne. Filrther downstream, the current slows and the river widens. Plants are able to take root in the muddy bottom. Fish, beavers, and waterfowl may find homes here. Kingfishers hunt for fish in fr~s.h water. T

As the ri vCT nows, it picks up sediments. Neilr the end of the river, called the mouth, the water drops its sediments and becomes murky. Clltfish and carp may li ve in these dark waters. Ponds and lakes are made of still wllter. Some Me small and may disappear during dry spells. Others, such as the Great Lakes, are huge. 1Jcep ponds and lakes have three different zones. Algae, plants, insects, and fi sh live near the sun-wa rm ed surface. Farther down, the water is cooler, but some sunlight shines through. Here lh'e plankton, which is a general term for many kind s of tiny organisms that live in water. Fish and other larger animals feed on the plankton. Still farther down is a zone that is deep and cold. Bacteria and other decomposers break down dead plants and an imals. What are three tvpt's of

Ir~hwate r Kosyst~ms1

Review

o MAIN IDEA What factors distinguish one biome from anothef?

Oiffer~nt biom~~ h~v~

different
Water
a VOCABULARY "What is a

biome? tist si~ e~amples of biomes.

f) READING SKill..: Text St ructure Use your outline of this lesson to summarize the biome of your choice.

o CRITICAL THINKING: Analyze

"Why aren't marine alg.ae found at depths below 200 meters? How doe this influence li fe at these depths?

o INQUIRY SKILL: AnalYl e Data Which land biOmes have a greater temperature range during the year, those near the equator or those in temperate regiOflS?

.,t TEST PREP Unlike freshwater ecosystems. marine biomes are A. salty.

MATH Find an Averag e Annua l rainfall in

B. dry.

a particular rain forest is shown in the table below. What was the average rainfall over the five·year period? Year 1 250 em

Year 2 240 em

Year 3

no em

TECHNOLOGY

Year 4 260 em

Year 5 250 em

GatherData Set up a rain gauge and record precipitation levels for one week. During the same period, use a thermometer to record temperatures. Explain how your data relate to the type of clima te found in your biome.

C. sunny. D. ful l of life. ~

'iii.

Technology Visit w_.eduplacuomlscpl fond our more 31.>001 bO~.

10

Literature Earth's ecosystems inspire writers of both fiction and science. Compare these two selections about the Everglades of Florida.

Some Rivers by Frank Asch Some rivers rush to the sea . They push lind tumble and fall. But the Everglades is a river wit h no hurry in her at alL Soaking the cypress thai grows so tall; nursing 11 frog, so 'luiet and sma ll;

she flows but a mile in the course of a day, with plenty of time to thin k on the way. Bu t how can she cope

with the acres of corn ilnd sorrowful ci ties that drain her? With hunters and tourists a nd levees that chain and s tain and pain her? Does the half of her that's left think only of the past? Or does she think of her fu ture and how long it will last? Some rivers rush to the sea. They push and tumble and fall. Bu t the Everglades is a river with no hurry in her at alL

READING

River of Grass Prologue to Everglades: Buffalo Tiger and the River of Grass, by Peter Louri e

In Ihe early sixteenth century Ihe Spanish explorer Ponce de Lc6n searched thc coast of Florida for Ii'll' Fountain of Youth. He never discovered the mythical fountain, but if he

h
huge, silent river. The E\'crglades. called Pa-hay-okee. or "Grassy Water:' by the Miccosukee (ndi,ms. is often only inches deep, yet i t runs a hundred miles from Florida's La ke Okeechobee to the Gulf of Mexico and Florida Bay. In places il is seven ty m iles wide. It has been called II nver of grass because of the dense waves of tawny sawgr
l TALK ABOUT IT Wha t do you thin k should be done to protect the Everglades?

What Is a Food Web? Why It Matters... What did you have for breakfast? like this owl, you get the energy you need from food. food energy (omes ultimately from the Sun. It is then passed through an ecosystem by

living things.

PREPARE TO INVESTIGATE

Inquiry Skill Use Models When you use models, you make and ana lyze a structure or picture representing a real,world

process to bener understand how the process works.

Materials • different·colored peI1cils • Investigate photo card

Science and Math Toolbox F« step 2, review Making a (hart to Organill' Oata on page H11 .

Model Energy Flow Procedure

o e

Hypothesize Look at the photo card of living things. It includes grass, zebras, and a lion. Form a hypothesis about how each organism obtains its energy.

Use Models In an ecosystem, energy from food passes from one organism to another. Producers get their energy from the Sun. In your Science Notebook, make a

chart like the one shown. Which organisms

e

in the photo are producers? Draw the producers in the bottom level of the chart.

Use Numbers Producers get 100 units of energy from the Sun. Write th is number

of units on the chart. Note that producers use 90 percent of these units for their own life processes.

o

Use Models Wh ich consumers eat the

e

Use Models Which consumer eats other

producers? Draw the consumers in the next level of the chClrt. Record the amount of energy available to them. They will use 90 percent of this energy. consumers? Draw this consumer in the top level of the chart. Record its available energy.

Conclusion 1.

Use Numbers How much energy is left for the living things that eat the producers? How much is left for the last consumer?

2.

Infer

Why aren't there more levels in the chart? Explain.

II

Resear<:h The model you used is called an energy pyramid. Use the Intemet or library to research energy pyramids. What happens to energy as it is passed from one living thing to another?

v

af1l by

Reading

VOCABULARY f ood (hain food web

p. 815 p.826

READING SKILL Classify As you read,

s.ort groups of living things according to their ro le in a food ...

Energy Flow MAIN IDEA In an e(o~ys lem, energy fl ows fro m produ(crs 10 ( onsume' s t o dcwmposers.

Energy from Food Would yOll li ke to make food from a gas in

the air and water from the ground? You could do that- if you were a plant. Plants are Earth's producers, as arc algae and cerlain bacteria. A producer ma kes its own food from raw materials and energy.

Plants and other producers use the energy of s u nlight, changing it into chemical ene rgy. Water

and carbon dioxide combine into sugars and oxygen. Sugars are the food for the plant. Plants use some of these sugars 10 grow, and store the rest

in their tissues. When you ('ill a plant, you t.l ke in energy the phln t s tored. You (lnd (Ill other (lnimals are consumers. A consumcr gels cnergy by c(l ting food,

not producing it.

plants a. e p. odutelS. in most

Food Chains To better understand feeding relationships, scientists organize the living things of a commu nity into food chains. A food chain describes how energy in an ecosystem flows from one organism to another. Almost all food chains begin with the Sun. Producers, such as green grass, capture the Sun's energy to make food . Animals th nt eat plants, such as a cnterpillar, are called first-level consumers or primary consumers. These animals eat plants or other producers. The birds are 5eCond-levcl consumers. They eat other consumers. The cat is a third·level consumer. Notice that nil the consumers rely on plants. Wi thou t plants, there would not be a food chain.

Which other organisms playa role in a food chni n? If phmts and animals die withou t being eaten, organisms called decomposers will break down the remains. Decomposers inc lude bacteria, some protists, and fungi, as well as earthworms and other small animals. They seTve to return an organism's tissues back to the soil for new organisms 10 usc again. In e\"ery ecosystem, different producers, consumers, and decomposers are constantly filling their roles in food chains. You, too, are part of food chains. When are you a primary consumer? Are )'OU also a 5eCond-level consumer?

~Ijm"'. iii

Comp,ue a p.odu(e. ""d

(on~ume,.

Decomposers DKompmers break clown tlMo dKaying 1.....1M of dead

ploducers and

Food Webs

Cycles in Nature

LikE' you, ITl()St animals take part in mol"{' than onE' food chain. For example, do cats eat only birds? No, cats also eat mice and fish. A food web shows how food chains combine in an ecosystem. Look at lhe food web on the opposite page. The algae, 11l'i;'"S, and smaller plants are produ«rs. The mou5C eats plant seeds, and it also eals insects. The snake eats insects, 100, bu t it also ca ts mice. The hawk hun ts both mice and sna kcs, and SO docs the fox. By studying food webs, scientists can explain how ecosystems function. They also can predict the effects of changcs to an ecosystem. [f the hawks all lefl the ecosyst('m shown hel"{', how do you think the other ammals would be affected ?

Food chains and food webs show how energy nows through an

Cla u ifying Consumers Most consumers playa similar role in every food chain Ihey are a pari of. A rabbi t, for example, is always a primary consumer. [I is an herbi vore, meaning ~ plant eater. N Other consumers are second- or thi rd-level consumers. Examplcs include hawks and snakes. These animals are called carnivores. The wo rd cllmiwrl' means Nmeal ea ter. N Many (amll'Ores al"{' predators, animals that hunt and kill prey. A few anima ls, such as bears, cat both plants and animals. They are omnivores-the pl"{'fix olllllimeaning "all:' If you cat both plant and animal products, you arc (In omnil'ore, too. 826 • Chapter 4 • lesson 3

ecosystem. Ecosystems have many other in teractions, too, For example, as you learned in Chapler 2, plants take up carbon dioxide from the air and release oxygen. Animals do just the opposite-lhey release carbon dioxide and lake in oxygen. In this way, plants and anim.11s provide one another with the gases each needs. Another importan t cycle is the water cycle. All living things need water. Wa ler leaves Earth's surface through evaporation. It returns through rain, sleet, and snow. Nitrogen also cycles through ecosystems. Nitrogen is a gas that m;!kes up almost four-fifths of Earth's

atmos phere. All living things need nitrogen, but in II form differen t than nitrogen gas from the air. Fortunately, tertilin bacteria arc able to ~ fix " nitrogen gas into a form that plants can usc. Animals obtain nitrogen by eating plants. Bug-taling Plants Marshy soils typically have li ttle fixed nitrogen . To get the ni trogen they need, some pl,IOts take an interesting approachthey Neat" animals! When an insecllouches the toothlike fringes on a Venus "Ylrap, for example, the planl closes its leal'cs over it. These plants Irap insects not for their energy, bu t for the fixed nitrogen in thei r bodies. How do (onsumt!u and prodlKen inler;}(;1 in an lKos,": ':' :m: ' _ _ _ __

food Web Energy is traMfefJed from one organism to another in a food web. The afJOWS show the direction of energy flow.

An energy pyramid

.. lhird·levt!

shows how much

consumers (0.1%1

energy is passed along to titdllteding ltwl in an tcosystem.

.. Se(ond·level

consumers (' %1

.-~ ~-

Energy Pyramid What happens to the food you eat? You use the energy stored in food to wal k, run, and engage in many other acth'ities. A lot of this energy lea\'es your body in the form of heat. Any leftO\'er energy is stored in you r body tissues. You, like all living things, usc some energy, lose some as heat, and store some energy in tissues. An energy pyramid shows how energy flow s through an ecosystem. Notice tha t each 1C\'el is larger than the level above it.ln genera l. only about 10 percent of the energy in one level is passed on to the nex t. Producers, such as plants, make up the base of the energy py ramid. Primary consumers make up the nex t level. Second- and third-level consumers make up the next levels.

.. P
An energy py ramid explains a great deal about the populations of e<:o.iystems As a general rule, producers ha\'e Ihe largest populations because they have the most energy a\'ailable to them. Next in numbers are the primary and second-level consumers_ An ecosystem can support only a few third-level consumers_ The higher an anim.1.l's level on the energy pyra mid, the wider the range of land it must cover for food. This explains th e large hunting ranges of animals such as eaglcs, lions, and snakes. These animals all ha ve adapta tions to move quickly and to catch smaller animals. The energy pyramid also explains why food chains last only for three or four links. Beyond that, little energy remains for an animal to usc. What is an efH'!rgy pyramid ?

, • Lesson 3

Review Visual Summary Producers get the ir energy Irom th e Sun. All other livi ng things get their energy Irom producers.

A lood

chain show<; the flow 01 energy Irom one o.gan ism to anoth er. A lood web show<; overlapping lood chains in an e
Energy is lost as heat at each step 01 a food chain. An energy pyramid shows how much ene.gy is availab le for producers an d cOnsumers.

o MAIN IDEA Describe how energy flows through an ecosystem.

a VOCABULARY Compare a food chain with a food web. Use both terms to explain how an imals interad and depefld on one another.

() READING SKILL: Classify Give one example each of a produ<er, hemivOfe, carnivore, omnivore, and decomposer.

o CRITICAL THINKING: Apply

What would happen to an ecosystem if a drought killed half of the plants mat lived there?

o INQUIRY SKILL: Use Models List the th ings you ate for breaklast today. Use the list to
.,tTEST PREP Unlike a carnivore. an hemivore A. makes its own food.

MATH Make a Graph Only 10 percent of the energy in one level of a food chain is passed on to the nex\. Mal:!! a graph showing energy movemen t in a four·level food chain. Assume 100 units of energy at the lowest level.

HEALTH Make a food Pyramid Humans need to eat differen t types of loods to stay healthy. Research the basic food groups and serving suggestions. Make a food pyramid that shows what you should eat each day.

B. eats only producers. C. eats other animals.

D. eats both plants and animals. ~ Technology . . Visit w_.eduplace.comlscpl 10

fond 001 more abool food web!..

Walruses blush a lot, but not because they're embarrassedl It's just their way of staying comfortable in their cold Arctic biome. Walruses have a thick layer of blubber that keeps them warm in the ocean. Out in the Sun, all that padding makes them hot. So when they sunbathe, their hot blood rushes to the surface to let off some heat. The walruses turn bright pink. Hippopotamuses turn pink too, but in a very different way. Hippo skin ooa:es reddish slime. This slime is an adaptation to the hot dimate of their African biome. The slime keeps the hippos' skin from drying out under the powerful tropical sun. It works as a sunscreen too. The best part is that the hippo never has to remember to put it onl

READING

: Compare and Contrast

Keeping cool I. II full-time job

for hippos. All day they do little but wade. They don't ewen

.at. Only at sundown do they lumbe ..

out of the 1'1"... to graze 'n comfort on the

Th.,. overgrown teeth are no usa at all for chewing, but they make handy tools In a frozen world. After. hug8 meal of clam, on the ocean floor, walru ••• u .. thel .. Ihal"p tusk' to haul them"I ..... onto the '~::;;-.Iippery ice. ..

-

Chapter4

Review and Test Prep

Vocabulary Complete e.;( h sentence with a term fro m th e list. 1. A(n) __ shows overlapping food chains in an ecosystem. 2. Zebras are an example of a{n) _

of living things in an

ecosystem. 3. The flow of energy from producer to first-level consumer to s{'(ond·level consumer can he shown using a simple __ 4. Different populatioos 01 living things found in the \.arne area at

the same lime form a(n) _ S. A(n) __ includes living and nonliving things interacting together.

6. Ecosystems with similar cl imate and vegetation make up a(n) _

7. Temperature and precipitation determine the __ of an area. 8. The __ biome has long, severe winters and short, (001 summers. 9. Prairies and !>avannas afe the two main types of __ .

biome Bll community 87 climate 812 dese" 814 ecosystem 86 food chain 825 food web 826 grasslands 814 population 88 taiga 815 temperate forests 813 tropical rain forests B13 tundra BIS

10. __ has a faye.- of frozen ground calii'd permafrost.

' Test Prep Write the letter of the best answer choice. 11 . About _ percent of the energy available n . Very limited populations survive in Eanh's drie-st __ at one level of an energy pyramid passes to the next level. A. tropical rain lore-sts A. 10 B.30 C. 60

D.90

12. Tropical ra in fore-sts are __ year round. A. cold and dry B. cold and wet C. warm and dry D. warm and wet

B32 • Chapter 4

B. grass lands C. taigas D. de-sl'lt5

14. Trees that lose their leaves in cool fall weather are common in _ A. tropical rain fore-sts B. tel1l!ll'fate rain lO!'ests C. taigas D. de-sl'lt5

Inquiry Skills 15. Classify How do scientists classify a

marine biome into th ree zones? In which zone must populations survive both above and below the water? What happens in this zone? 16. Analyze Data The table below shows

climate data for two cities in the United States. What biome do you suspect each city is a part of? Explain. You may choose to graph the data to organize it. Temp: Average monthly temperature ("F) Precip: Total precipitation (inches)

MOIIIII

CIty • CIty'IM'IPI'I'I.dp. 'fM11PI'I". cill.

".

54/0 .7

~41 2 .7

March

62/0. 9

3412.7

M~

79/0 .1

5713.1

July

94/0. 8

1113.1

Sept.

86/0 .9

62H.5

Nov.

6~ /O . 7

4113.8

17. Apply [)(oscribe four ways that you

interacted with living and nonliving things in ecosystems today. 18. Analyze If you wanted to show energy

ftow in an ecos~tem. would it be best to use a food chain or a food web? hpla in your answer. 19. Evaluate Your friend comments that

bacteria are all unhealthy. What coold you say to improve his understa nding of bacteria? 20. Analyze Which animal receives more

energy from a producer: a first·level consumer or a second· level consumef7 Explai n.

Performante Assessment Display a Biome Ma~e a display that shows a typical scene from a biome.lnclude at least fOOf different types of living things. The display may be a deta iled drawing. poster, Of diorama. Write a paragraph or short essay to accompany the display.

Map the Contept RII the terms below into the concept

map. Each oval represents a larger group than the oval inside it Biome Comm uni ty Ecosystem Organism Populat ion

c

)

LESSON

1

living things live on the highest mountains and in the deepest oceans. How do they survive in such different places? Read about it in lesson 1.

Decreases in food supply, changes in climate, relocated species- how do these factors upset the balance of an e cosyste m?

Read about it in lesson 2. LESSON

3

Swamps turn into meadows, meadows turn into forestshow do living things respond to changes in ecosystems?

Read about it in lesson 3.

What Are Habitats and Niches? Why It Matters ... How (an a downfish live so dose to the sting ing tentades of a sea anemone? The fish rubs against the anemone, (Dat ing its scales with a kind of slime. The anemone doesn't recognize the coated fish as food .

Living things interact with one another in all sorts of ways. These interact ions are key to understanding

how they survive.

PREPARE TO INVESTIGATE

Inquiry Skill Observe When you observe, you use your se nses to describe

the properties of objects and events.

Materials • safety goggles • e~rthWQrms

• goldfish

• • • •

2 aquariums soil organic matter apple peels • fish food

Worm and Fish Habitats Procedure Safety: Wear goggles when handling soil.

o Collaborate

Work in a small group. Half till one aquarium with soil. Spread a

thin layer of decayed leaves o r other organic matter over the soil. Add some earthworms and a handful of apple

o

peels. Moisten the soil. Wash your hands afterwards.

Measure Fill the second aquarium with

water at room tempe rature, almost to the top. Add the goldfish and fish food.

o

You may also add small rocks and plastic plants. Wash you r hands afterwards. Observe Each day for a week, observe the earthworms and fish. How do they move?

What do they eat? How do t hey affect

o

t heir environment ?

Record Data In your Science Notebook, write your observations in a chart like t he

one shown.

Conclusion 1. 2.

Infer What body parts make the fish well suited to their environment? How are the earthworms suited to thei r environment?

Predict Could the fish live in the earthworms' environment? Could the earthworms live in the f ish's environment? Why or why not?

Inve$tigate More! Research Learn aoout an interesting plant or animal that lives in the wild in your state. Where does it live? What role does it fill in its ecosystem?

\.eaf~ by Reading VOCABULARY adapta tion habitat niche sym biosi,

Habitats Niches

...""

MAIN IDEA Each kind of organ ism occupies a particular niche in lIS habitat.

p.B39

p.8'2

Habitats

READING SKILL

To tell people where you li ve, you probably use

Compare and Contrast

As yoo read, compilfe allCl COIll1asl relationships among : different organisms and their :

.

en .... rQlIfTII!I.ts,

. :

• • • •• ••

a street address. An address is a simple way to describe the loca ti on of you r home. All livi ng things h.-we an "address," a place they live in. This place is called a habita t. A habita t is the area where a n o rganism Iivcs, grows, and develops. Everything that an organis m needs to survive can be found in its habitat. Ma ny diffcrcn l livi ng th ings may live in the same habitat. The African savanna, fo r example, is ho me to zebras, lion s, and m'InY o ther nnim:lls.

Savanna Habitat

The niche of a lion in

a savanna Includes

Niches Have you seen pictur<'S or movies of workers at an automobile factory? Every worker has a place to be and a job to do. If one of them fails to do his or her job, everyone else's job is affected. Organisms in a habitnt have specific fUt"\Ctions, too. A niche describes wha t an organism docs in its habitat. You can think of a niche as a job at a factory or a role in a play. E.1ch organism plnys a certnin role in its h3bitat. Look 3t the Silvanna habitat shown below. The zebras 3re consumers. They ent producers, such 3S gr3SS. They drink water from the watering hole. These nre parts of their niche. Zebras are also food for lions. That is 3nother p3rt of their niche. Zebras nnd lions sh3re the same habitat, but h3\"e different niches.

Niches describe more th3n just feeding relationships. A niche includes exactly where in the habi tat an organism lives, how it reproduces, how it protects itself, and how it behaves. For eX3mp\e, birds in the s.wanna may Ih·e in nests. They ma y use sticks, mud, and other materi31s. Part of th('ir niche includes r('Cycling such materials from their habit31. Each group of organisms in a habitnt uses resources in different W3)'S. Zebras, for example, eat the grass. Lions do not ('at grnss, but th('y lie in the grass. Birds use the grass to build nests. Because each group uses the same resources in different ways, there are enough resources for e\'eryone. However, changes in ecosystems can upset this bal1mce, as )'ou'l1 team in the ncxtte:'l5Ofl.

.:> (OMPUE AND (DMTUST

Ho.... do

habitats and niches compare?

The niche 01

a zebra in a savanna incl\ldes

~Ptatjons

I

n":!hat if you see iI drawing of a large, white pola r bear crossing a hot, sandy desert? Something's wrong with this picture! Can you explili n what il is? The thick fur and heavy padding of a polM bear help it Slay warm in its cold, Me tie habitat. Desert animals, on thc other hand,

have body paris that help them stay cool. These characteristics arc called adaptations. An ad aptation is any characteri stic that helps an organism survive. Sometimes adaptations are phySicaL The turtles in the pictures on this page are good examples of similar animals wi th d ifferent adaptations. The desert tortoise has legs that help it mo ..." eilsily across the sand. The sea turtle has nippers that help it move through wa ter. E.1ch animal's body is physically adapted to its habitat. Plants ha ve adaptations, too. For example, a " IctuS'S leaves are thin, pointed spines. Its bod y, or stem, has a very thick outer layer. These adaptat ions help the cactus conserve Wilier in its dry habitat. Other adaptations are beha\'ioral. This means that the organism has certain behaviors that help it survive in its habitat. A bat, for example, migh t sleep through the winter. This adaptat ion, called hibernation, allows the b.ltto live in cold climates.

Cacti Most plan ts would wilt and die in a hot desert. Catti survive because of their waxy stems. long roots. and

Se a Turtle . The flippers of a :lea turtle are adapted for swimming.

Desert Tortoise . Tile feet of a desert tortoise are adapted for walking In sand.

Natural Selection How do organisms develop adaptations? In the mid-ISOOs, British naturalist Chilrlcs D.m"in proposed a theory to ~lp explain the process. According to Darwin, some members of a species have characteristics better suited to the envi ronm('t1t thiln other members. These individ uals are more likely to survive ilnd pass on their ch:lracteristics to their offspring. This process is known as natura l selection. Let's examine how it works. Picture a rocky beilch. A population of birds searches among the rocks for food . Some of the birds ha\'e long, pointed beaks and can easily pick up pieces of food from cracks between the rocks. Other birds han' shorter, more rounded beaks and cannot reach food. Which birds are moll' likely to survive on the rocky beach? Which birdS:lre more likely to reproduce? The birds wi th the pointed beaks are more likely to do both. Thus, their chilTacteTistics are passed on to thei r offspring. After scveral generat ions, many moll' of the birds on the beach will ha\'e pointed beaks. Most scientists believe tha t natu ral selection accounts for the amazing \'iIriety of living things and their adaptiltions. Scientists also usc the theory to predict now species might change in thl> fu tul"('.

~

What is an adaptation? Compare adaptations among different Ofganisms.

• Why does a sandpiper have such a long, thin beak1 A{(ording to the theory 01 natural selection. traits that htlp an animal survive be-come more common in the population.

The dense, shaggy hair of these yaks helps them survive the bitterly (old weather 01 the Himalaya Mountain~ •

Parasitism A hookwo,m takes blood and nutrients from its host . It benefits. and the host is ha,med.

Commensalism

Mutualism

An elf owl ma kes its nest in

Cleaner shrimp eat parasites a113ched to fisll. Both the shrimp and the fish benefit Irom this relatio-nship.

a hole in a cactus. The owl benefit$. and the cactus is not affected .

Symbiosis All living things depend on and affect one another. Sometimes the relationship is very close. Symbios is des<:ribes a close, long-lasting rc!ationship between two different kinds of organisms. This word means "living together." Parasitism is one type of symbiosis. One organism, called the parasi te, benefits from living off the \xxIy of another organism, the host. For e xample, a hookworm benefits from living inside the digestive tract of a larger host, such as a dog. The dog may become ill, but it usua lly doesn't die. If it did, the hookworm would die, too. 842 • Chapter 5 • Lesson 1

In commensalism, one organism benefits and the o ther organism is not affected. Birds called cattle egrets, for example, follow cattle as they move through a field. The birds cat the insects that jump from the grass as the ca ttle graze. The birds benefit, while the cattle are neither harmed nor helped. In mutualism, both organisms benefit. Cleaner shrimp, for example, eat parasites off fish. The shrimp get food and the fish stay healthy. This relationship helps both the shrimp and the fish.

>:',"

COMPARE AND CONTRAST

t hree

ty~ s

How d o the of symbiosis compare ?

Review

o MAIN IDEA Describe two A na tmal habitat is th~ area where an organism lives. It provid~ everything the organism neetis to survive. A niche describes the role of an organism in its habitat. Adaptations are traits that help o.ganisms survive in their habitats. Adaptations can be physical Or behavio. al.

Symbiosis is a d ose. long·lasting relationship between organisms. The three main types of symbiosis a.e parasitism, commensalism, and mutualism.

different niches in a sa~anna habitat.

a VOCABULARY Give an example of an adaptation. Describe how the adaptation helps the organism.

f) READING SKILL: Compare and Contrast Accord ing to natural selection. how do diffe.-ences among organisms h{>lp develop adaptations?

O CRITICAL THINKING: Apply How would you describe your niche in your family? How does it compare to an animal's niche in nature? " INQUIRY SKILL: Observe Describe a type of symbiotic relationship that you have observed. Identify which organisms benefit and which are harmed. if any.

.,t TEST PREP An organism's niche includes

A. whe.-e it lives.

MATH

Make a line Graph The table lists the bird population on an island lor 4 years. Plot the data on a line graph. Describe the changes you observe. Year

'00

'01

'02

'03

'1)4

Po p.

40

92

160

152

148

TECHNOLOGY

UseaMap Finda topographic map of your state or community. Use the map key to describe the physical features of habitats near you.

B. how it protects itsell.

C. how it repfOduce5. D. all of the abo~e.

~ Technology , . Visit www.edupI3(uomlscpl tof'rId out more about habftats arid niches.

What Factors Affect Ecosystems? Why It Matters ... How many wolves can live in

11

forest? The answer depends

on the size of the forest and the amount of food it provides for the wolves. Temperature can affect the populat ion, and 50 (an pollution. In

any population-ol wolves, trees, birds, or people-the size is limited by the available resources.

PREPARE TO INVESTlGATE

Inquiry Skill Hypothesize When you hypothesize, you use prior knowle dge or observations

to suggest 11 cause-and-effect relationship that can be teUed.

Materials •

III~d~uling

cup

• 3 plastic cups

• 32 lima bean seeds

...

• soil

• water . ~

• safety goggles

Science and Math Toolbox For step 4, review Making a Chart to Organize Data on page Hll.

Limits to Growth Procedure Safety: Wear goggles while handling soil.

e

e o •

Collaborate Work with a partner. Label the three cups A, B, and C. Place soil into the cups until they are nearly full. Each cup should contain roughly the same amount of soil.

Use Variables Place 2 seeds in cup A, Place 10 seeds in cup B. Place 20 seeds in cup C. Measure Measure and pour 25 ml of water into each cup .

Re<:ord Data Place at! three cups in a sunny spot. In your Science Notebook, make a

e

chart like the one shown for each cup. Observe Over the course of the next three

weeks, water the cups when the soil is dry and measure growth. Be certain that all the cups receive the same amount of water and sunlight. Record the date, height, and your observations at least

twice a week.

Conclusion 1.

Observe What differences did you observe in the growing seeds?

2.

Hypothesize What factor might have caused these differences?

3.

Use Variables Why was it important to give each cup the same amount of sunlight and water?

Design an Experiment Design an experiment to determine Itow sunlight affects plant growth. Remember to keep other variables constant, and 10 include a control.

v

afll by

Reading

VOCABULARY

."' p. BSt

extindion

populatio n predator prey

p. 841

ABalanced Ecosystem Different living things use the resources of

you read, look fOf cause· and-eflect relat ionships in populations and ecosystems.

(

(

• •

Main Idea The size of .my population can vary over time. It responds to changes in climat e and reSOllrces.

p.847

READING SKILL (;t ... se ;tnd Effect As

(

Changes Population

) )

)

an ecosystem in different ways. They take some resources from e<:osyslems and add others to it. A balanced ecosystem has enough resources for all of its living things. Every ecosystem supports m,my populiltions. A population is all the organisms of II given species thallivc together in the Slime area. Any change in one part of an ecosystem can upset the balance. For example, suppose a fungus kills many of the plan ts thai rabbi ts c.,1. Such an even t could lower

the rabbit population. This would affect the hawks, owls, and other animals that eat the rabbits. On the other hand, if a popula tion of rabbits be<:omes too large, they might crowd out other species that live in the area. J3ccause ecosys tems have limited resources, they can support only a limited number of living things.

Predators that «,"sume frog eggs help keep the frog population from growing too large.

In a predator-prey relalionsl1ip, tile two populations tend to rise and fall together.

""

1975

""

""

Limits on Populations In any ecosystem, populations are always changing. Old animals dk.>, and new ones take their place. When a tree falls, plants Ih31Ihri\'c in sunlight can begin to gmw. Other dhll1~t:~,

huwevcr, Ci11l up:sct the

b.1lancc of the ecosystem. Consider the relationship between

pr('d ators and their prey. Predators are animals tha i hunt and eat other animals. Prey are animals hunted and eaten by predators. (n a healthy e(:osystcm, the population densi ties of predators and prey are balanced. Bul certain fac tors can upsellhis balance. One ('xample comcs from an act ual ecosys tem-Isle Royale, an island in l..1kc Superior. Moose first appeared on the island around 1900. They may h,we crossed on ice tha t formed a temporary bridge from the mainland. The island had plenty of plan ts for the moose to cat, and no predators. The pop ula tion of the mOOS
have enough food. Food is a limi ted resource In an ecosystem. SO, Ihe limi ted food supply on thc island help<'d slow population grow th. In 1950, wolves appcarW on the island. Wolves are prWators of moose, so the moose population dropped while the wolves increased. Yet after a wh ile, the wolf population dropped because not enough moose remained to support them. With fewer wolves, the moose population rose agai n. As the graph shows, the populations of these two species con tinuoo to rise and fall. Lack of preda tors can make an ecosystem unbalanced as prey populations grow unchecked. Add ing preda tors is one way to restore the bala nce.

~ nUSE ANDUffCl

How might a de
"7

Changing the Balance Once changed, an ecosystem may take hundreds of years to recover. In some cases, it is chan ged forever. Some faclors that cause big changes in ecosystem s are living. Alien species are good examples. Alien species arc plants, animals, or other organisms Ihat arc not native 10 a given ecosystem. In some cases, an alien species has no nalural predators in its new home. II may thrive and "steal" resources from na tive planls and animals, or fced dire<:tly off them. How do alien species enler new ecosystems? O ften, they are broughl in by accid('nl. Zebra mussels, for example, traveled from western Russia to North America during the 19805 in water stored on a boat. The

-

... Zebra mussels anchor themselves to solid surfaces, including ot her organisms such as freshwater dams.

zebra mussels were dumped into the Great Lakes wilh the waler. By the 19905, the mussels had spread throughout many lakes and rivers. The tiny zebra mussels can clog water pipes used by power plants and water treatment facilities. Zebra mussels also harm native organisms. They grow in large groups on dams, mussels, and crayfish. This growth can smoth('r the native species. Another problem is th.lt z('bra mussels filt(,T the water, ckaring it of planklon. Plankton are tiny producers. With fewer plankton to cal and 10 provide oxygen, many native species die. It can Ix> very difficult to g('t Tid of an alien species. However, many states are working together to con trol the spread of these lroublesome organisms.

,

, The Asian long-horned beetle enteled the United Slates in wooden shipping crates in t he 199{)s.lt burrows un der the bark of trees. slowly kill ing them. <011

Nonliving things can also change the balance of an ecosystem. These include natural events, such as volcanic eruptions. For example, Mount SI. Helens is a volcano in the state of Washington. For many years, it was like a sleeping gian t- it caused no trouble. Hemlock and fir thrived on the mountainside, as did many animals. Everything changed in May 1980, when the volcano violently erupted. In a mailer of minutes, hot lava burned and destroyed trct'S over an area of 5(X} squ
Yellife slowly returned to the moun tain and neighboring areas. Some plants survived the eruption. Wind blew in seeds for grasses and shrubs, which sprouted a year or so after the eruption. Then larger plants moved in, followed by animals that ate those plants. In 2004. the volcano turned active once again, although the damage was not nearly as severe as before. If the volcano stays quiet for many more years, the forest will return as before. Other na tural e"enls include forest fires, floods, and droughts. Each can cause long-lasting changes in ecosystems. What do you think animals do when ecosystems change?

i'} (AUSE AND EFFlCT

Desc, ibe one way that a nonliving facto, may change an ecosystem.

When a new lizard moved into part of its habitat, the green anole 01 Florida moved to the treetops. A

Adapting to Change What if your home suddenly lost heat during a cold winter? What would you and your family do? You might mon' to a new home. Or you might adapt to the cold house, meaning you would find a way 10 Slill1ive there. Maybe you would build a fire or wear warm dothes. In nature, lil'ing things also respond to dramatic changes in their em'ironment. Sometimes they relocate, meaning they move to a new home. The mOl'e need not be far. For example, in recent years a lizard from Cuba inl'aded part of the Florida habitat of another lizard, th e green anole. The green anole used to live close to the ground. When it lost resources to the Cuban 1i~rd, the grct'Tl anole moved to the trectops. A lil'ing thing can also adapt to changes in its environment. For eKamplc, many animals grow thicker coats when the weather turns cold . • lessoo 2

If the change is too dramatic. howc\"er, the animal might perish, meaning it would die. Perishing is the consequcnce when living things can neither adapt nor relocate to su rvive a change. Living things h,l\'e relocated, adapted, and perished for as long as they have been on E..uth. Fossils give dues to how this happened. Fossils are the remains or traces of onceliving things. Fossils may not show how individual organisms changed, but they do sho w that different species have Jived at different times. Look at the fossil dinosaur shown below. No animal alive today has a skeleton just like this. Because dinosaurs could not survive changes in their erwironment, they perished.

Fossils help scientists determine how spe
Geologic Age

Conglomerate

Sedimentary rocks lorm in horilontal lay!!rs. Ov!!r tim!!, the layefs may bend, tilt, Of f!!main flat. '"

Evidence in Rocks Change in ffosystems can occur very rapidly and can afffft vast areas. For many animals, perishing is often the result. Throughout Earth 's history, not only have countless individual organisms perished, but so have entire species. When this happens, the species becomes extinct. Extinction occurs when all members of a species die out. Many different events can cause extinction, even among very successful species. How do scientists draw conclusions about species that wenl extinct long ago? They do so by studying both fossils and the rocks in which the fossils were found. The illustration above, for exam ple, shows layers of rocks from a hillside. These layers formed on top of one another over time. The oldest rocks are on the bottom, the youngest on top. Any fossils in the rocks must have formed at the 5.1me time as the rocks around them.

Taken together, fossils and rocks show that species and ecosystems have changed II great deal throughout Earth'S history. For example, fossil shells or fi sh show Ihe land once was underwater. Fossil ferns show a wet, warm climate. Both kind s of fossils have been found in mountains! Scientists are also able to estima te the age of a fossil, typically through a process called radioactive dating. The oldest fossils are billions of yea rs old. Sometimes the absence of fossils is key information. For example, Earth's rocks hold a wide variety of dino5.lur fossils, yet none in layers younger than 65 million years old. Scientists conclude that all the dino5.1UrS died at once at this time. Such an event is called a mass exlinclion. Ea rth has experienced several mass extinctions throughout its history.

D UUSE AND EffECT

What Can sci!!ntius t!!arn by uudying fossils and rock~? 851

• This map shows the utent 01 the glaciers in the Northern Hemisphere during the most recent ice ol9t, Irom about 20,000 years ago.

Climate Change Do you live in New York? Or Minnesota or Michisan? If you could tr11\'el back in time-say, 20,000 yea rs-you would not recognize these slates. They would be CO\' ered under a thi ck sheet of icc. Over the last two million years, large parts of North America and Europe ha\'e been covered several times by huge ice sheets, or gli'dcrs. These periods are called ice ages, The I"st ice age ended about 11,000 years ago. During an ice age, much of Earth's water is locked up in glaciers, causing sea levels to fall. During the last ice age, the drop in se" level exposed a land bridge bel\\'ccn Asia and North America. Mnny living things, humnns included, may have crossed this bridge to scUle in North Americn. 852 • Chapter 5 • l esson 2

Many an imals weT(' already in North America at this time. Some were very large, like the woolly mammoth and the saber-toothed cal. With their thick, furry coats, lhey were well adapted to the cold conditions. When the ice age ended, however, they be<::ame ex tinct. Some scientists belie\'e that these animals could not adapt to the warmer climate. Other scientists think that both climate and humans caused Ihe extinctions. Humans may have overhunted the great animnls. The exact reasons why some animals be<::ame extinct may ne\'er be known. But Earth's climate does change periodically. These changes greatly affect the living Ihings upon it. ~ (JUst AND UHO

How might climate

change affect living things in the future?

Review

o MAIN IDEA What factors can f(osystems have li mittd .esources. A balanctd ecosystem hil'i tnough .esOtl.ces to suppo.t all living things. Both living things, such as alien species, and nonliving things, such as volcanic eruptions, can upset the balance 01 an ecosystem. living things can respond to changes in ecosystems by reloca ~ l ng. adap~lng.

cause the size of a population of living things to change?

a VOCABULARY Use the terms

predator and prey in a sentence.

9

READING SKilL: Cause and Effect Why do alien spedes often thrive in the ir new ecosystems?

o CRITICAL THINKING: Apply Does your classroom have unlimited resources? hplain.

o INQUIRY SKILL: Hypothesize What changl?S in living and r.onliving things might be brought about by the onset of another ice age'!

or perishing.

.jJ TEST PREP A mass extinction occurs when

A. one animal spe
MATH Calculate Population Density Measure the area of your classroom. Determine the number of students in the class. Then calculate the population density of students in the classroom per square meter.

HISTORY Create a Time line Research major mass extinctions that have occurred throughout Earth's history. Make a time line showing when each extinction occurred and what types of organisms were affected.

C. many spe
Primary Source

DlNOSAUR

EXTINCTION Scientists have dug up dinosau r fossi ls all over the world. Yet the fossils always arc in rock layers older than 65 million years. Younger layers lack them. What killed the dinosaurs so quickly? Scientists continue to deb.lle this question! Two throries are outlined on the nex t page. Whatc\'cr killed the dinos.1.urs also seems to have killed more than half the species of the time-a mass ex tinction. Earth's ciim
might stem from th is long-ago event. The ast eroid theory of dinosaur extinction was put forth bV fathe,and-son scient isu : luis Alvarez (Ith) and Walter Alvarez (right). T

SOCIAL STUDIES

Asteroid Theory

Volcano Theory

All unusual amount of iridium is fOllnd in rod layen from the time of the maSS ... tinction.

Volcanic eruption, may have filled the air

Iridium metal is rare on Ea,th', surface, but mOre (ommon in asteroids. An asteroid strike might have filled the air with dust and deb.is. If sunlight was blocked, plants would have died, and dinosaurs would have followed.

with snot and ash, blocking the Sun. The volcano theory argues that extinction took

place more gradually. pl'rhaps ove. seve.al million yea.s. The thof)' also explains the i,idium deposits. because Ea, th', interior is IIigh in iridium.

I. READING (HECK How do scientists infer that dinosaurs went extinct quickly?

2. WRITE ABOUT IT Comp
3. TAlK ABOUT IT Do you think Earth is in danger of another mass e~ tjnctjon?

How Can ns Change Ecosytems? Why It Matters... Huge numbers of bison once

roamed the Great Plains of North America, Yet in the 1800s. humans hunted them almost to extinction. Hunting and other human activities changed not only the bison, but the «osystems of wnich they were part. Changes like this continue today. By underst anding how and

why ecosystems change, people can manage those changes wisely.

PREPARE TO INVESTIGATE

Inquiry Skill Predict When you predict,

you use observat ions. facts, or patterns to ant icipate results.

Materials • plastic container wirh lid • ice cubes • modeling d Jy

• waler • metric ruler

Science and Math Toolbox For step 2, review Measurenwnts 011 page H16.

\twestigate

Rising Sea Level Procedure

o

Use Models Work with a partner. Use clay

to make a model slope inside a shallow plastic container. The slope represents a coastal area. It should be placed at one

e

end of the container. Measure Add water to a depth of 2 em

inside the container. The water represents the ocean. It should cover only the edge of the slope.

o Predict

Add four ice cubes to the container. The ice cubes represent gladers. Cover the container. In your Science Notebook, predict what will

e

happen to the level of the water when the ice cubes melt. Record Data The next day. measure the

depth of the water in the container, Record your measurements in a chart.

Conclusion 1.

Observe What happened to the depth of the water in the container?

2.

Observe How was the model land affected by the change in the depth of the water?

3.

Predict How might a rise in sea level affect coastal areas?

Inve,tigate More! Research

I~

Earth's aVl'fa.ge temperature increasing? Research this question, Ptepafe a report thaI includes a graph or map to display data.

v afn by Reading VOCABULARY endangered

p. BS9 spe
..'"

Human on Ecosystems Mll in Id ea Human activi ties impact ecosys tems in both positive lind negative ways.

READING SKill

Human Activities

Draw Conclusions As you

Rain forests are among the most valuable resources on Earth. They are home to a vast vari(>ty of plants and animals. Yet rain forests are destroyed every day, By one account, almost 200,000 squnre kilometers (77,000 S<Juare miles) are losl each year.

read, draw conclusions about the impa
e-ccsystems.

That's about 37 city blocks per minu te! People clear rain forests for land to grow crops, raise livestock, and build homes and businesses. Lumber th1lt comes from the trees is valuilble, too. Why should you be concerned about the loss of rain for...sts? One re
Tropical rain forests are being cleared for farm ing and Jogging. Many species are lost along willi llie forests. "

animals may become extinct when their habi tats are destroyed. Scientists believe that some rain forest plants may contain substances that could be used as medicines. In add ition, rain forest plants release oxygen and take in carbon dioxide from the atmosphere.

• Oi!velopers cut the lOp off a hillside to build these houses in California.

Humans have a huge effect on ecosystems by destroying habitats. In fac t, hnbitnt loss is the mnin renson why r
• In the United States alone, more than 4 billion kg (9 billion Ibs) of fish are caught each year. Many popular fish are now threatened .

Excessive hunting and fishing practices pose another threa t to many ecosystems. In the enrly 1800s, for exam ple, more than 60 million bison ro.lmed the Great I' lnins. Yet by 1890, fewer than a thousan d were left. O verhunting was the bigges t reason. People killed the bison for th('ir hides or tongues. Wh('J1 a species is close to becoming extinct, it is called an endangered species. When a species is close to becoming ('ndnngered, it is called a t hreatened species. These cn tegories are importan t. They le t everyone know which species nCl"'d the most protection.

11)

DRAW CONCLUSIOIoiS

Is h-abitat

destrud ion a serious problem7 hplain.

r

Types of Pollution

Air Pollution F.cIO,if'S that bum fossil fuels c.n ,.. leMf harmful substances into the ai.,

Wat er Pollution Oil §jIiIl! c.... harm plants ind animals Ih;it live in Of ~ar il'>f' watH.

Land Pollution Trash Bnd garbage ale oflen ca relessly dis(a.M.:i, polluting lilt land. 860 • Chapte, 5 • lHSOl'l 3

Pollution Whll! ot her human atlh'ities ca n im pact ecosystems? Burning fossil fuels is one example. Fossil fuels include oil, gas, and C0.11. These fu els contain 11 lot of energy ilnd are eaSy to use. However, burni ng them can cause pollution. Pol1ution is the add ition of harmful substances to the environment. When fossi l fuels are burned, certlli n gases and solid particles are relclIsed into the air. These polluta nts ca n milke the air unhealthy to breathe. Some combine with wa ter droplets to form adds. They fall to the ground as acid rain. Fossil fuels don't have to be burned to pose a threat to the environment. Oil, for e~ample, is often transported on bLg shLps called tankers. Accidental spills ca n damage the environment and be e~pensive to clean. About 3OO,COJ bird s died following a major oil spill in Alaska in 1989. Human activities ca n also pollute the land. Each yea r, people In the United States produce hundreds of millions of ton s of solid waste, including paper, plasti cs, and metals. Most solid waste is buried in S.1nitary landfills, and some is burned. However, people sometimes carelessly dump solid waste along roodsides or in bodies of water. Some farming and lawn-care practices can also cause pollution. Rain can wash fertili zers into rivers and streams, where they ma y damage the ecosys tem.

Growth of Human Population Hundreds of yea rs ago, the effects of human activities were rela tively small. There were no power plants or motor vehicles. And the hum"n population was much smaller than it is today. As the graph shows, today's human population is very large, and growing larger all the time. In 1800, onl)' about I billion people lived on Earth. By 1930, that number had doubled. A mere 30 years latC!", the popullllion had increased to 3 billion. Today, more than 6 billion people live on the planet. Modem humans have been llround for thous,1nds of years. Yet our popullltion growth remained fairly steady untillhe 11lst 200 years. Why has the human population grown so fllst in such a short time? Advllnces in medicine and technology hllve mllde it possible for more people to survive diseases and accidents. These s.1me factors help people Iive longer lives.

E\'eryone needs food, clean water, clean ai r, shelter, and other resources. As you've learned, however, ecosystems h.we limited resources. If the human population con tinu es to grow, not enough resources will be a\'ailable. In fact, in many parts of the world, food and wa ter are already scarce or poorly managed. Remember that human activities can harm ecosystems. A growing human population will take up more space. More natural habitats will be lost. More species wHi be threatened wi lh extinction. Can anything be done to help this situation? Read on to find out how people are protecting the environment. ~, DRAW CONClUSIONS

How has the growth in human po~la lion affected e.:osysttms around the world?

A growing human population must compete

IOf a limited amount of resources, such as

E~~=:;2:;;food' land, and waler.

-.,• • •- •• -• , •

! i0

•

0

'""

"" Year

''''

GoodNews

~~-r~~:-~~~~~~~~--l

All around Ihe world, people are working to reduce pollu tion and restore damaged ecosystems. Governmen ts arc passing laws. Industries Me laking action. And people li ke you are making a difference everyw here!

~ DUW (ONClUSIONS How can in divi dual actions he lp protect the environ ment ?

In the United Sta les, wildlife refuges

cove, nearly 40 million he
Cleaner Cars The ( lean Air Act, revhed in 1990, limib

the pollu tants from new (ars. Some manuf"durers have designed Ur'I thai use altemilliv!' fuels.

Endangered Species Act This le<jisla t ion protects endangered and t hreat ened spe<:ie'S from harm by

human ad ivitie§.

5 • Lesson 3

I

,

,

.

\

~

.

Clean Technology

Community Actions

Hew IKh!Wlogy

MallV people wa.k to dun up trash,

burning power

'~ces poIlul~1s i t

coal·

pl~nlS.

plant trees. or carpool to school and work. Individuals Can m.. ke a big cliffe.enn t

Protecting Wetlands The Environmff'ltal ProlKlion

Environmental Legislation

Agency (EPA) W(Orks with state and local governments to prot«! bogs, swamps. and otht< _1 plac:H.

o. support Io
Many states have passed laws to p'otKt funds from license platn help p.OIKI -,~

•

B6'

•

Review Visual Summary Many habitats are destroyed by logging. developmen t and other human actions. Overha .... esting un redu(e the populations of certain species. Pollution affects air. wa ter. and land. A growing human population means that more people are competing for limited resources. GovelOments have passed laws to protl!'Ct the environment. Many industlies use !leW tl!'Chnology to reduce pollution, Individuals can help dean up ecosr.;tems.

for Home and School

MATH Make a Table Read the information about human population on 861 and make a table to show this data. About when was the world population at 4 billion?

WRITE Explanatory Use the library or Internet to research how i ndi~iduals can help the environment. Make a "Help the Environment" booklet. Share the booklet with classmates.

5 • Lesson 3

o MAIN IDEA What are some ways that people affect ecosystems?

6

VOCABULARY What can happen to a threatened species if its population continues to decrease?

o READING SKILL: Draw

Conclusions (an the actions of one person help the environmenl? Explain your answer.

o CRITICAL THINKING:

Synthesis A plant in a tropical rain fo.rest be
"

INQUIRY SKILL: Pre di ct

How will Earth's resources be affected if the human population (ootinues to grow?

.elEST PR'P During the past 100 years. the human population has A. decreased.

B. stayed the same. C. increased slightly.

D. increased greatly. ~ Technology .... V;s;t www.eduplace.comlscpitofiod out more about pollution.

Entomologist Between 7,000 and 10,000 new species of

i n~e'ts ilfe

discovered every yearl Entomologists study insects to learn

'-. - how they behave, function, and relat e to other organisms in different ecosystems.

Entomology is important for many reasons. Insects recycle nutrients. pollinate crops, and provide food for

larger animals. Other insects threat en food supplies or

spread diseases. What It Takes!

• A degree in entomology or biology • An interest in insects and their environments

Ship's Captain Boats and ships are visitors to water e
A ship's captain needs to understand the ship and its cargo, as well as the environment through which they travel. The job comes with great responsibility. What It Takes! • An understanding of sea-going vessels and ocean navigation • leadership and management skills

Wham! What a punch!

Can it a shrimp, but for Its slu, It's the hardest hitter on hrth. The mantilshrimp socks a punch that approaches the force of a bulletllt can smash through the armOr of the toughest prey in the blink of an eye. In an aquarium, a mantis shrimp can spell trouble for the ecosystem. Why? It rapidly shatters and uls all the snails and other shelled crutures in the tank. And good luck getting rid of this powerful puncherl The mantis shrimp is smart. It knows how to hide and strike out from behind cover. It can easily break a person's finger-or even the tough safety glass of a public aquarium.

READING

: Compare and Contrast

Sock it to 'em! A human boxer is no match for the mantis shrimp. In the blink of an eye, the shrimp's club-shaped front leg

can reach SO mph. That's two or three times faster than the fastest human pI.mcher!

Vocabulary Com plete each se ntence wi t h a term from the list. 1. A{n) __ is the aru..vhert an organism lives.

aNptation B40 endangered speciH 859

2. Wheo a spedes is very dose to becoming exlina. it is called 0(0) _

utinrtion BS 1 habitat B18

1. Pn'dalOfS hunt and eal _

nidle B39 pollution B60

• __ is the number 01 living things of a certain species in a g~area.

population B46 predator B47

5. A{n) __ is an Ofganism's role itI its habitat. 6. Burning lossilfuels and dumping trash can cause _

847 sJmbiosis B42 threatened !lpec:iH BS9 jWeJ

7. A lion is an example of a(n) __ that hunts zebras. 8. The "iPPM on a sea turtle are an example of a physkill _

g. __ occurs when alilhe members of a certain species die off. 10. Parasitism. commensalism. and mutualism are types of _

~ Test Prep

Write the letter of the best answer choke. 11 . Whill best describes a spe
be classified as endangefed if illosl more _1

13. In lhe process 01 _

organisms that are best suited to their environments survive ilnd piiss on tIleir traits to their offspring.

A. extinct B. Ihriving C. OIl..,

A. natural selection

D. tlftal@llfd

D. behavioral adaptation

extinction C. niches and habitats 8 . ITIiISS

12. Potentially harmful orgMisms that are not na~ 10 a given Kosystem are called _ A. pr@da1OB B. al.., Sjlecies

C. parMiles D. lhrealenfd

""'" 868 • Chliptt r 5

14. W11ich 01 the following is NOT a wiI'f that

humans atlect ecosyslems? A. poIlllIion B. de<\;fl

,met.1

C. eartllquakfs D.~ling

Inquiry Skills 15. Observe look around the area in which you live fOf examples of how humans have changed local ecosystems. Write a short paragraph describing these changes.

17. Synthesizing What might be do~ to stop the spread of harmful alien species? List three ideas and discuss why they could work.

16. Predict A fire destfOyed a forl'St. Aft!!!"

18. Appfying What are some th ings you can

a year, grasses began to grow back in the area. Soon after tilat, rabbits moved in to eat the grass. The rabbits had no major predators. so their poIJulation grew. Recently, f(lxI'S and hawks returned to the area. Predictllow the population of the rabb its will cilan(;e.

do to help the environment? How could you encourage people to join you?

19. Evaluating Is it helpful to classify organisms as endangered or threatened? Why or why not? 20. Anafyzing Humans. other mammals. and birds can maintain a constant body tempe!'ature. Why is this a useful adaptation? How does this explain the !.pread of these animals around Earth?

Performance Assessment Make a fossil Use clay to make a mc:>del fossil. Select an object such as a leaf arK! press it into the clay. Or, trace the outline 01 an animal's footprint in the clay. Exchange your model with another student. What can you infer about the plant or animal from studying the fossil?

Map the Concept Fill in the concept map by writing definitions IOf

each term. S~mb ;oti(

Relat;omhip'

[

Para,it;'m

,

-r

Commen, ali,m

(

Mutuali , m

I

)

Write the letter of th e beu answer choke. 1. A hookWOfm lives by using the nutrients in a dog's digestive system. Whidl typI! of

symbiosis is this1

4. Which factor is MOST imponant in creating the difference in biomes? A. physical features B. temperawre C. planllife O. climate

5. Which is Earth·s largest land biome1

A. commensalism 8 . mutualism

C. organism O. parasitism

A. desert 8. grasslands C. lundra O. laiga 6. The marine OI'ganism shown lives in the

2. Which is Ihe st(ond·level consumer in this

food cllain?

A. bird

B. caterpillar

A. shore zone.

C. fox

B. inlenidal zone. C. near·shore zone. O. open ocean zone.

O. leaf 1. Which is NOT a reason thaI rain forests should be preseMd? A. B. C. O.

810 -

They contain many producefS. They are home 10 many habitats. They are good for growing (fops.

They contain many different organisms.

un0

7. The illustration below ~ part of a forest Kosystem. Whidl is part of the Kosystem but IIOt part of till' forest community?

Answer th e following in comple te sen tences. 9.

What is a IniISS extinction? Give two examples of what might cause a mass extill(tion.

10. Explain what an alien species is and how the introdllttion 01 an alien species can affect Kosystems.

A. rod:

8. grus C. mouse D. bird

8. The illuSlJation below is MOST likely a

A. taiga I>iome. B. tundra biome. C. desert biome. D. grusland biome.

."

Grasslands tan be hot and dry in the summer, with temperatures sometimes climbing over 38°C (100°F). Animals t hat live in hot plates must find a way to keep tool. The jatkrabbit's long ears are adapted not only for hearing, but to help cool its body.

A jackrabbit's ears are

about 20 cm long. The wind (oots the ear's thin s~ in. whK:h cools blood vessels Iyirlg dO'lely beneath.

Othe< ki nds of rabbits cannot survive high temperatu res. They would sofie< fatal he"t strokes at tempe
Snowshoe hares live in coid, Arctic climates. Small ears help trap l>ody heat inside.

All orga nisms have adaptations to h ~p them survive in their natural habitats.

Adaptahons include physical features. such as ear shape and leflgth. as;ffil as behaviors.. such as leed irlg at night instead of the day. Ma ny organisms are adapted to very specific habitats. If their habitat is de5troyed.lt1ey may not survive elsewhe<e. Learn more about adaptations. Go to www.eduplatuom/stpifore...... mples of othe< adaptatklos that help animals and plants surviole.

872 • Unit B

Earth Systems Chapter 6 Earth's Changing Surface ................................... C2 Chapter 7 Earth's Structure .............................................. C34 Chapter 8

Using Resources Wisely.................................... C70

Independent Reading

Wind, Wat~f.

and Ice

San Francisco Shakes

Global Energy

Ea rth's surface is (onstantly (hangi ng. When a strong earthquake strikes, the surface shakes and rolls. Other earthquakes are ha rdly felt at all. How do scientists measure t he strength of earthquakes? You will have the answer to th is quest ion by t he end of t he unit.

LESSON

1

Features of Earth's surface range from deep

ocean trenches to tall mountains. What are these features like?

Read about them in Lesson 1.

Wind, water, ice, and gravity- how do these agents wear down Earth's surface?

•

Read about it in lesson 2.

LESSON

3

Shifting sand, bubbling lava, moving crust, and flowing ice-

how do they build up Earth's surface?

Read about it in Lesson 3.

r

What Makes Up Earth's Surface? Why It Matters ... The next time you're at the shore, take a dose look at th e sand along the water's edge. At one time, those tiny grains may have been part of the rocks that made up a hilltop or

mountainside. Understanding Earth's different features (an help you identify, enjoy, and protect them.

PREPARE TO INVESTIGATE

Inquiry Skill Compare When you compare, you describe how two or more th ings afe similar and how they are different.

Materials • modeling day • 1 shlillow squlIre plio • paper

• dental floss • plastic kni fe

Model a Map Procedure

o Compare

A topographic map has contour

lines. These lines connect points that have the same e levat ion, which is distance

o e e

above sea level. St udy the topog raphic map of a hill shown here.

Use Models Add clay to the pan and make a model of the hill. Refer to the picture

and the map. Measure With a pencil, mark contour lines on the model hill. Use the topographic map as a guide. Then use a plastic knife or dental floss to slice the hill in layers along the lines. Set each layer aside.

Communicate PIClce the largest layer on a sheet of paper and trace around the

edges. Then trace the other layers to create a topographic map.

Conclusion 1.

Compare How are the sliced layers of your model like the contour lines in the map?

2.

Use Models Look at the topographic map. Where is the steepest slope? Where is the flattest plain?

3.

Infer How are topographic maps useful? When might you use such a map? Design an Experiment

Use day II) mooel anl)lha landfl)rm. CUI and trace ilS layers II) make a lo>p(lgraphic map.

v afn by Reading VOCABULARY (ontour lines

Earth's MAIN IDEA Earth's surf"ce indude s W
,.lIst

9· CIO p. C1

topographic map

p. CIO

READING SKill Main Idea and Details As

you read. write details aboot Earth's surface features.

landforms. You can identify surfilce features by Iheir location , shape, and elevation.

A Watery Planet Ea rth is the only planet in our solar system wi th a large amount of wa ter on its surface. Most of thai water is found in the oceans, which are vast bodies of sail water. All of Earth's oceans are connected,

forming one great world ocean. Most of the world ocean is in the southern part of the planet.

The world oceiln surrounds the con tinen ts, which are huge landmasses tha t rise above the ocean surface. Most o f the waler on the continen ts, called inland water, is not sal ty. Water with little $..111 is called fresh water. L1kes and rivers are the major surface fea tures tha t hold or c~rry fresh water. Rivers, streams, ponds, and other smaller fea tures also hold fresh water. Plants, humans, and o ther animals all need fresh water. Yet only about three percent of Earth's water is fresh wa ter. And most of this is found underground or locked in glaciers or ice sheets near Earth's poles. For these reasons, fresh water is a very important resource.

stand alton att other solid surfitC~ futurH.

C6 • Chapter 6 • Lesson 1

Earth's Solid Surface Earth's rocky ou ter larer is called the crust. Different features make up the surface of the crnst. These f('atull'S are found on the continents and on the ocean noor. Continental features are often called landforms. Mountains are thc tallest of Earth's I1mdforms. Their steep slopes rise to

lall peaks. Mountains can be found as single peaks or in chains, ranges, and mountain systems. Six major mountain ranges form thc Rocky Mountllin system.

Hills are smaller than mountains. Although hills do not rise as high as

mountains, their rounded crests still st
Pkt-

How 0:10 plateaus

(ompalf 10 moonl~ins and hill!:?

Plateaus are high landfonns with fairly flat surfaces. Plateaus are often found along the tops of canyons and can extend for many miles on either side of a canyon. Mes.1S are similar to plateaus, but are much smaller. The word mes
sl ~

of Earth's

Coastal Features As you travel from the middle of a continent toward the coast, different landforms appea r. In North America, the Atlan ti c Coastal Plain e~ tends from Canada all the way to Rorida. This coastal plai n slopes gently from the Appalachian Mountains to the shores of the Atlantic OcC'an. Beaches and marshlands are found at shorelines, where dry land meets the oce
Pocket beaches form along a rocky co..,stline. These beaches are small and cu rve landward, with sand filling spaces, or "pockets," between rocky cliffs. They are common in New England and the Pacific Northwest. Mainland beaches are qui te different from pocket beachC'S. They are found along straight shorelines that are free of large rocks. Some mainland beaches stre tch for miles. Long, s., ndy beaches are also found along barrier isla nds. These islands are separated from the mainland by a narrow, shallow body of water. B.1Trier beaches rn.'y be qui te large. Rorida 's Miami Beach is a large barrier beach. So is the beach at Atlantic City, NC'w Jersey. S.,nd dunes are mounds or ridges of s.'lnd that the wind often fonns along coastlines. They often fonn in long, irregul
Contal plaiM are tow· Iy\I>g ..-eM ..... t 510pe gently from

r~~:-":" __":-:::~:-:-"" the mainland towaNl C8 • Chapter 6 • Lesson 1

the $hole.

Ocean Floor Features Starling at the water's edge, the continental margin extends to the deep ocean floor. This feature consists of three parts: the continental shelf, the continental slope, and the continenta l rise. The continental shelf forms the edges of a continent. A shelf normally slopes grlldually down from sea level to a depth of less than 200 m (660 ft). The width Clln nmge from less th;m 80 km (48 mil to more than 1,000 km. Beyond the shelf is the steeper contincnt1l1 slope. It can fall to depths of 3 km (1.8 mil and range from 20 km to 100 km wide. The slope forms the sides of the continents. At the bottom of the slope is the continental risco This region stretches out about 1,000 km lIcross the ocean floor. The ocean floor hlls 11 variety of features, some similar to those found on dry land. For example, Hudson Canyon slices southeast through the continent1l1 shelf stlIrling from 11 point ncar New York City. Such canyons are known as submarine canyons.

As the graph shows. oceans cover most of Earth's surface.

Moun tllins and plains arc present underwater, too. Seamounts are huge, steep-sided moun tains rising from the ocean floor. Some sellmounts hllve flat tops. They are know n as guyots (G EE ohs). They once may have risen lIbove the water's surface. Over time, they were worn down and co\'ered by rising water. Seamounts occur mainly on the deep ocean floor. This VllS! arell is known as the abyssal plain. ',

MAtN IDEA

From the shore to the ocean floor, what are the three parts of the continental margin ?

Mid-Ocean Features

Mapping Surface Features

Many striking features of the ocean floor occur in the ocean basin, the region beyond the con tinen ta l margin. In the ocean bnsin, deep canyons called trenches plunge into the ocean floor. The Mariana Trench, near the Pacific island of Guam, drops nearly I I km (6.6 mil below the ocean floor. Mid-ocean ridges form a mountain chain that runs more than 56,000 km (33,600 mil through the world ocean. Parts of the chain have di fferent names. These names include the MidAtlan tic Ridge, the East Pacific Rise, and the Mid-Indian Rid ge. Most mountains in tile mid-()C(>a n ridges reach more than 1,500 m (4,950 ft) high. Some peaks sti ck out of the water as islands. A number of the ridges have deep, steep-sided valleys down their centers. These valleys create a ragged, rough su rface on the ridges. The sides of the ridges slope down to the abyssal plain.

A topographic map is a map that shows the shape of surface features and their elevations, ! MOUNT or heights above sea level. Contour lines connect points on the map /' that ha\'e the s.1me elevation. By studying con tour lines, you can learn the shape and steepness of the land. This topographic map shows Mount Rainier in Washington State. The numbers on the contour lines show elevation in feel. The sp<1cing of the lines shows how steeply the land slopes.

~INI~

~) MIIN Inll Wha t do contou r tin es show abou t tandfor ms?

)

Review

o MAIN IDEA What thr~ - 1

hrth has many types of surface features both On dry land and under water.

properties are used to identify surface features?

a VOCABULARY How do contour lines help you visualize a feature of Earth's solid surface?

f) READING SKilL: Main Idea Oceans cove r most of Earth's su rface.

and Details Name and des.cribe the thr~ parts of the continental margin.

o CRITICAL THINKING: C -"

Topographic maps help picture Earth's features. Contour lines show elevation.

Analyze Earth has lots of water. Walet covetS more than 70 percent of Earth's surface. Even so, wa ter is a critical resource for all living things. hplain why.

o INQUIRY SKILL: Compare

Describe how plateaus and plains are similar and how they are different.

.jJ TEST PREP

MATH

Calculate and Compare The mountain chain formed by mid·ocean ridges stretches for more than 56,000 km. How many miles is that? (1 km = 0.6 miles)

TECHNOLOGY

Mapping the Ocean Scien tists map the ocean floor by using sonar, a technology that uses sounds to measure distances. Research sonar and its many uses.

The Mariana Trench is a feature of the floor of the Pacifjc Ocean. What land feature does its shape most resemble? A. river valley

B. canyon

C. mountain range D. beach ~ Technology , . . \lisit www.eduplacuomlscp ltofiod out more about Earth·s features.

(11

How Is Earth's Surface Worn Down? Why It Matters... Weathering and erosion change Earth's surface every day. Sometimes

these changes take place very quickly, but often they are very slow. The rock formation shown here took thousands of years to form .

Understanding how and wny Earth changes is the key to preventing or influencing the changes.

PREPARElO INVESTIGATE

Inquiry Skill Predict When you predict,

you apply facts you know, observations you have made, and cause-and-effec! relationships you understand.

Materials • IIdil

• • • •

milleral kit 2 plastic bowls eyedroppt'f vil'M'9'lr

• hand lens • safety goggles

Science and Math Toolbox For step 4, review Making a Chart to Organize Data on J)age H1 1.

Rock Erosion Procedure Safety: Wear goggles du ri ng this activity.

o e

o

Experiment Using a nail, scratch th e calcite over a plastic bowl. In a separate bowl

repeat the procedure with hal ite. The re should be a small pile of dust in each bowl. Predict What do you th ink will ha ppen t o the minerals when t hey come in contact with vi negar? Write yo ur predictions in yOU f

Science Notebook.

Observe Using an eyedropper, add 3-6

drops of vi negar to the calcite. u sing the hand lens, Observe the react ion. Do the

same in the bowl (Ontaining halite. The n

o

wash your hands.

Record Data Draw a picture of the calcite and halite reactions in your Science

Notebook.

Conclusion 1.

Compare How do the react ions of the calcite and the ha lite differ"?

2.

Predict Based on your data, predict how acid rain can break down or weather rocks. How do your results support this prediction?

3.

Infer Why are most caves and caverns formed in limestone, a kind o f rock made from calcite?

Inve5tigate More! - -I Design an Experiment (an water break apart rods when it freezes into ke? Find out in an experiment with dlali(, wate.; a plastic bag. and a freezer.

v afn by Reading VOCABULARY erosion

p. C16

sediment w ea t hering

p. (14

p. (14

READ ING SKill Sequence Use a diagram to re
DOD

Down

Earth's MAIN IDEA OemU;:Iive forces. such as weathering and erosion, wear down Earth's surface feawres.

Weathering Earth's crnst is mostly solid rock. The rocks are broken into pieces by processes of weathering. Weathering is a destructive force, or a force that breaks down something. There are Iwo types of weathering: mechanical and chemica l. Mechanical weathering is the breaking of larger rocks into smaller pieces of rock, called sediment. In cold climiltes, ice plays a major role in this process. As waler freezes, it expands. When water trickl es into the cracks of rocks, it can break the roc~ "p"rt when it freeze,. Moving air and Wil ler il lso enuse mffhanical weathering. As blown sand or rushing wil ter hits rocks, the rocks weaken. Over time, they crac k or crumble. Even living th ings can cause mechanical weathering. Plnn t roots cn n grow th rough cracks and break apart roc ks. Burrowing animals push against rocks nnd nllow water to move deeper into rocks and soil, where freezing and thawing can weather rocks. Sometimes rocks will peel into sheets. As soil nnd rocks nre removed from a buried rock, pressure on the rock is reduced. T his may nnow minerals in the rock to expand. An outer Inyer of the roc k will peel away. Eventually, other layers mny nlso cruck and flnke.

Trees have tile power to move or split rocks as they grow.

Cave Formation

Weak acids formed in rainwater seep into the ground. where they weather rock.

(ave~ are a re~ult of weathering. "

Over tim e. holes are produ(e(!. Eventuall y. the holes grow in to (aves.

Although mechanical wea thering breaks rocks, it docs not change the type of rock. In chemical wealhering, rocks change into other mlllerials. Water is the main factor that causes chemical weathering. Water can dissolve some minerals that make up rocks. Wa ter also dissolves certain chemicals from the air and soil to form a \\'eak acid. This acidic water can easily dissolve certain minerals. The type of minerals in rock also affects wea thering. For example, weak acids dissolve limestone and marble more easily than some olher minerals.

Generally, a combination of differen t types of weathering is at work in a region. Most weathering takes place at or ncar Earth's surface. However, wa ter trickling through the ground ca n affec t roc ks far beneath the surface. Caves are underground hollow arens crea ted by weathering. Large caves are often called cnverns. Most caverns arc made from limestone. Weak acids seep into the ground un til they reach a lOne soa ked with water. As the ground water becomes more acidic, it dissolves minerals in the roc k. Over time, holes are produced in the rock. The holes grow, creating paSs.lges, chambers, and pits, and eventually become caves. At first, the caves are full of water. Over time, the water drains away.

if,

SIQUINC!

How can w ater from the surface create a cave?

River Valley Formation

OAshallow sueam gradu ally erodes its t hannel.

f) The stream grows into a river. whith tanies sediment away Irom its bilnks.

O ln time. the river t uts a V·shaped valley.

Erosion Weathering is the process tha t brea ks down roc k into smaller pieces called sediments. The carrying away of sediments by moving water, wind, or moving ice is called erosion. A common agent of erosion is water moving down a river. The river begi ns as a shallow stream, often at a high elevation. Gravity moves the water downhill. As it flows, the rushing wa ter erodes the ground, dissolving minerals and pic king up sediments from the streambed. Over time, the river channel becomes wider and deeper. Usuattya stream joins other strea ms to become a river. The increasing flo w of water and tumbling rocks further erode the river channel. This process may carve out a steeper or wider valley. In some cases, rapid CU ll ing of the valley floor in the upper part of a river can create il canyon. Further along its course, the river gains mo re water. The water broadens and deepens the river channel. ( 16 • Chapter 6 • Lesson 2

A mountain stream in California weathers rocks as it rushes over them. It carries sediment downstream. "

Over time. rivers create the deep V·shaped valleys known as canyons.. •

Frozen water also wears down and shapes Earth's surface features. ThouS.1.nds of years ago, glaciers helped to sh~pe the rolling plains in the northern United States. They also carved out the Great Lakes. In arctic regions and in high mountains, gl
Melting gladers left many takes behind . ...

Ocean waves ~nd currents also erode Enrth's surfnce. Crnshing waves break down rock along coastlines. The sediments nrc d rngged back nnd forth, slowly turning to sand. Wind nnd waves from the open ocean nlso batter headlands. Hendlands arc narrow se<:tions of lnnd that jut out into the ocenn. Usually they arc cliffs of hard rock. Wnves curve around the hendlnnd, throwing up sal ty water and pebbles. Grndually this movement erodes crac ks in the hendlnnds, forming sen caves. Sen caves on both sides of a hendland mny join to form n sen nrch. As erosion continues, the top of the nrch may collapse. The ocean side of the arch is left standing alone. This single column is called a sea stack.

~"j.jI!m.

Describe one way that erosion wears down Earth's surface.

A sea arch forms when sea caves on both sides of II headtand join . •

Slow and Fast Changes The ongoing process of erosion keeps the landscape changing. In general, such destru ctive forces act very slowly. However, sometimes such changes happ"n much faster. You read that chemical weathering creates caves in certilin types of rock beneath Earth's surface. This process can take thouS
buildings on them ~Iide, too. This landslide look place in soutllern California. T

Sinkhole is a very desuiplive term: Land above weathered rock si nks Into a hole. Tills sinkhole affected central florida . ...

Landslides also occur suddenly as the result of erosion. In fact, they can happen in minutes. Landslides are lilrge movements of land that tumble down il steep stope. Mudslides, rock fall s, an d avalanches are eXilmples of landslid('S. Although gravity is the main cause of a landslide, other destructive forces are involved. Erosion from rivers, rain, glaciers, or ocean water may steepen a slope and loosen sediments. If the sediments beocome 5O.1 ked with wate r, they may slide more easily. Any disturbance, such as a minor earthquilke, can create cracks or shake rocks loose. This action can start landslides. Volcanoes can also ca use hmdslid('S. Volcanic eruptions can deposit ash and other materials on steep slopes. Heavy rains added 10 this material can CilUS(' il land slide. How does a landslide occur ?

Review

o MAIN IDEA Why are

weathering and erosion considered 6estructive forces?

hrlh'~ ~mfit(e feature~

are worn down by destructive forcts, such as weathering and

a VOCABULARY 'What are

sediments? Give an example of sediments and how they IOfm.

e r ~ion,

Water, wind, and the action~ of plants and animals all can cause weathering,

f) READING SKilL.: Sequence Describe the sequeflce 01 events in the formation of a cave.

o CRITICAL THINKING: Infer How could you tell if a glacier had once moved across a region?

In erosion, wtathered rock is moved by wind, water, ice, or gravity,

Destructive forces usually act to change Earth's surface slowly but can also cause rapid chang es to Earth's surface,

o INQUIRY SKILL: Predict

Would the features 01a marble statue last longer in a dry desert region or in a warm, moist region that has heavv Industry? EltJllain your reasoning.

~TEST PREP Which 01 these is the strongest ageflt 01 chemical weathering?

A, plant roots

B. acidic water C. burrowing animals D. freezing water

MATH

Solve a Problem You observe a giant wave crash on the rocks. After 1.5 se
WRITING

Narrative Plan a trip to the Grand Canyon, Glacier National Park, or Carlsbad Caverns, Research your chosen park. What activi ties will you participate in? What sights will you see?

I-t '¥

Technology Visit www.edupl
Primary Source

cleopatra's Needle How can weathering and erosion change rock? One ancient stone obelisk- a kind of tall statue-prollides a very interesting example.

In appreciation for help in building the Suez Canal, the ruler of Egypt presented the United States an obelisk that was more than 3,000 years old. This obelisk is now called Cleopatra's Needle. It was installed in Central Park in New York City in 1881 .

The obelisk remains in the same spot today, but it has changed drastically. Much of the outer surface of the stone has worn away, blurring inscriptions that were clear when the statue arrived. Look at the photos of Cleopatra's Needle and

a similar obelisk that remained in Egypt. In 1881 , the two looked much alike. How afe they different now ? How do you explain these differences? For a hint. compare the graphs of temperature and precipitation in the two locations. ~'

?'I>...... ,~\-...,..,.'"c ,::-____ l uxor. ~.

"\

".

Egypt

New York City Cleopa tra's Netdle W!lS movtil in 18.81 110m Egypt to New YorIc (ity~,_..,.

( (20 • Ch.aplt r 6 • l Hson 2

)

SOCIAL STUDIES

Climate Graph for New York City

,.. + -u ".

-,, ,

•• •

••E

The graphs shaw average temperature and precipitation far New York City and Luxar, Egypt. How do the
!'C,~ompaC"C'_·_,

-• -i E 0

".

'"

'.! • ••

". ".

• ""

•

Month

Climate Graph for luxor, Egypt

" " ",

-• -

,,

•

".

-u+ ". -•, ,

• • ••

••E

".

'"". ".

• "" , •• ,

,, , ,• • , • • • • ~ • --• •" z >

0

0

0

Month

Sharing Idea. I. READING (HECk How has Cleopatra's Net!dle changed sinte it came to New York City? Compare it to the obelisk that stayed in Egypt. Egypt The Obelisk of Ramesses II has remained in Egypt since ancient times. ~

2. WRITE ABOUT IT Study the climate graphs. Compare the climates of the two plates. 3. TALK ABOUT IT How do you explain the differences between the two statues?

E 0 < 0

••

'5. 'j •

How Is Earth's Surface Built Up? Why It Matters ... The more people understand

about the (,luse and effect of changes to Earth's suriace, the better they can manage those changes. People can work with nature to take care of Earth's surface and enjoy

its features.

PREPARE TO INVESTIGATE

Inquiry Skill Infer When you infer, you use facts you know and observations you have made to draw a conclusion.

Materials • soil • ~Iuminum p~n

• pencil

• paper cup • 001111" of water

Set Up a Streaming Slope Procedure

o

Use Models With a partner, build a soil slope on o ne end of an aluminum pan.

The slope (a n be steep or gentle.

If)

o

RK1lrd Data Draw a picture of the soil slope in you r Science Notebook.

Predict You will drip w ater from a paper cup onto the soil at the top of the slope. Predict w hat you think will happen. Re
C)

Experiment With a pend l, poke a small

hole in the bottom of a paper cup. (over the hole in the cup with you r finger. Have

your partner fill the cup with water from a water bottle. Hold the cup 3 to 4 em above the soil at the top of the slope. Rem ove your f inger and let the water flow

over the soit slope.

Cit Observe

What happened to the soil7 Draw a picture and describe the changes in your Science Notebook.

Conclusion 1.

Compare Look at the two pictures you

drew of the soil slope. How are they alike and different? Do the pictures support your prediction about what would happen when you poured water o nto the slope?

2.

Infet'" What can you infer about the way water and gravity wear down and build up Earth's surface?

Investigate More! Design an Experiment Make another soil slope. This time. pour wale!" from the bottle down me slope. How do the spI'flI and amount of wale!"
Earth's

VOCABULARY

p.C14 READING SKILL

Cause and Effect Use a

chart to show the effects of constructive forces on Earth's surface.

DO

•• • •• • ••• •• •

MAIN IDEA Forces such as deposition an d volcanic activity build up Earth's surface features,

Deposition Have you secn wavcs gently lapping at a sandy beach? Waves are pMt of th .. wason that beaches haw sand. Ocean waves and currents drop sand on n bench in a process called deposition. Deposition is the dropping. or releasing, of sediments that have been moved from one place to another. Sand is sediment made from rocks or shells that have been ground into fine grains. Both erosion nnd deposition arc gradunl processes. However, erosion is a destructive force, meaning that it wears down the land. Deposition

is a constructive force, meaning that it builds up the land.

Deposition helps cre
Alluvial fans and de ltas are formed when l ivers slow suddenly and their sediments are deposited . .6.

D CAUSE AND EFFECT

Why is sediment deposited as the slope of a river bed levels out?

As a river flows across a flat plain, its course begins to wi nd in ( urves (ailed meanders . .6.

Pushing Up Earth's Surfac. Surface features can be pushed up from below as well as built up from above. Not far below Earth's surface, temperatures are quite high. In some places, the conditions are hot enough to melt rock! Melted rock below E.uth's surface is called magma. Magm.1 o riginates

in a layer of Earth just below the crust. Pressure below thc surface can cause magma to push up on E.1Tth's cru st, creating round, dome-shaped mountains. In some places, magma can work its way up through thc cru st and flow oul on to Earth's surf,w:c as lava. As lava flows, it cools and hardens

In some places, ('fIough la va will build up to form a huge deposit with

gently sloping sides. Such deposits are called shield oones. Shield cones o flen form on the ocean floor. For e xample, th e Hawaiiml Islands arc actually the tops 01 several giant shield cones. The base of Mauna Loa, the largest 01 these cones, is about 4,500 m (15JJOO ft) belo\\' the surface of the I'adlic Ocean. Its peak rises over 4,100 m (14JJOO It) above the ocean's surlace.

into rock.

Compare this view of Hawaii from the International Space Stalion t o the illustrati on below.

~

r--' Mau~ loa

Building Islands The Hawaiian Islands consist of II selies of shield cones that e~tend from the flool of the Pacific Ocean to well above its surface. As the cruU continues 10 move ovel the magma dome, new mountains form . ... L~l

110 t SPOI

o one The Himalaya5 began forming when plate of Earth'5 cruu cruhed into

O fOr million5 of years, the plate5 have

another plate.

A different constructive force created the Himalaya Mountains These mountains in Central Asia are among the highest on Earth. The Himalayas began forming about 65 million years ago when huge sections of Earth's ernst moved into each other. The pressure caused the crust to fold. Other features of Earth are made from the remnins of living things. For example, the chalk cliffs of l)(wer, England, arc made up of shells of tiny S(>a animals. These shells were deposited on the sea floor millions of years ago. When forces below the ernst raised the sea floor, the chalk deposits bccnme chalk cliffs.

Atolls are ring·shaped islands formed from deposits of coral skeletons called coral reefs . ..

continued to push together, folding and uplifting to form mountains.

Coral reefs are another type of formation produced from the remains of living things. In shallow Iropical walers, liny animals cnlled corals gather in colonies. As corals die, their skeletons build up into a bumpy ridge called a reef. In some Pacific Ocean waters, reefs are built around volcanic islands. Sometimes an island will sink, but the cornl continues to grow. This creates a barrier reef S(>parale from the island.

)0"',"

CAUSE AND EF FECT

How were the Himalaya Mountains formed?

Glacial Deposits ThouS3nds of years ago, snow fell year-round over large areas of Asia, Europe, and North America. Over time, the weight of snow from the top added pressure below. Slowly, the snow turned to ice. Glaciers were formed. The ice in some of these glaciers was almost a thous.and meters thick. The ice's weight became so great that it pushed and den ted the land. ThCS(' moving masses of ice were tremendous forces of erosion. Huge amounts of soil and rock were pushed ahead of the ice and ca rried along in the glacier's bottom layers. After thousands of years, the ice began to melt. The glaciers reached their presen t positions about 11,000 years ago. As the ice melted, it left behind a changed landscape. The rock material deposited by a glacier is known as till. Till may be silt, s.1nd, gravel, boulders, or sharp rocks. Some till is picked up as a glacier scrapes Earth's surface. The glacier drags till along its icy base.

Eskers form from streams that flow along the bottoms of melting glaciers. A

A glacier also deposi ts till at its fronl, or snou t. Such deposits are called moraines. Long Island, New York, is the lerminal moraine left when the last ice sheet melted. The melting water carried s.1nd and clay away from Ihe snout. Today, the sou thern portion of Long Island is sandy, while the norlhern portion is rocky. Streams flowing through tunnels in melting glaciers deposit sand and gravel in ridges, too. These winding ridg(>S are called eskers. I

CAUSE AND EffECT

How do gladers

deposit sed imen t?

In high mountains, glaciers can carve out bowl-shaped hollows called cirques . ...

Review

o MAIN IDEA Compare Earth's constru
Deposition build~ up sur/act featurts w(h as sand dunu, alluvial fan~ and rivtr dtltas.

a VOCABULARY Why is

Magma pushing up from Earth's mantle (an create islands and mountains..

O READING SKILL.: Cause and Effect What causes the creation of dome mountains?

deposition 6escribed as the opposite of erosion? Give examples of these processes.

o CRITICAL THINKING: Mountains (an alw form whtn tectonic platM collide, folding and lifting upward.

Cirque-s. moraines. and eskers are formed by glatial deposi ts..

Synthesizing In Hawaii, some beaches are covered in black sand. What can you conclude from this fact?

{) INQUIRY SKILL: Infer What can the size and shape of a sand dune tell you aboutlmw it was formed?

.,e TEST PREP When a river meets an ocean, sediments drop out of the river be
B. slows OoWll.

MATH Solve a Problem

A pilrticular glacier moves about eight centimeters a year. At this rate, how long will it take the glacier to move one kilometer?

SOCIAL STUDIES Makea Map The state 01 Hawaii is made up of a (hain 01 islands. Resear(h Hawaii. What unusual plants and animals live there? What are some benefits and challenges of living on an island? Crea te a poster to present your findings.

C. becomes saltier. D. flows uphill.

Q~:~~:I.~lu~la(uom'sCP'

find out more
IQ

What a drop!

You' re looking down Into one of the deepest canyons In the world. In fact, this c.. nyon system Is so deep .. nd Y.wst It w.. s n .. med the Gr.. nd C.. nyon. How did the Grand C.. nyon form? Erosion. The Color.. do River has been steadily we .. rlng its w.. y Into the plat...u undern ...th it for millions of y... rs. Wind, rain, gravity and other forces h .. ve helped sh .. pe the canyon walls. The result Is. n.. tural wonder. The Grand C.. nyon winds more than 270 miles .. t an av.r.g. depth of 4,000 f •• t. In some places, If you could throw a rock far enough out. it would f.lI mor. than a mil. b.for. hitting bottom.

READING

: Compare and Contrast

At the Grand Canyon's

de epett point, it would take four and a half Empire

State Buildings stacked on top of each other to r each the rim!

.----.

• -----1

------

•

-----.

--

. ---

--

-~--

---'"

-

Vocabulary Complete each sentence wi th a term from the list. You may use each term more th iln once. 1. _ is a (OfIStf'1.ICtM! Iorce. 2. A map that shows the shapes of Earth's Iaodforms is a _

3. The rody outer ~ of farth is called the _ 4. A topographic map has _

contour IiIlH (1 0 (rust

(7

deposition C2. erosion Ct6

that COflnect places that h<we the !>aITIE'

elevation.

5edionent (14

topogrllphic

m.., 00

weathering Ct.

5. Weathering and __ ale destructive forces. 6. Moving water. wind, and ice calry weathered rods awiTt in a process called _ 1. Sand and other tiny pieces of rod are moved by el'osion and wttled

by -

8. Tiny pie<es that form from the weathering of rocb are _ 9. Watel' is a common agent ot both weathering and _

10. The process known as _

I

can be mechanical or chemical.

Test Prep

Write the fetter of the best answer choice. 11 . location, shape, and elevation help define 13. Vokanic activi ty is an e~ample of _ Earth·s _ A. erosion B. c(lIl$tructive force A. C(lIl$Il"\H:tiYt loren 8. destruclivt' forces C. surfiKe fNtures D. sediments

12. Erosion and weathering are examples

,1 -

(32 •

C.

~theriog

D. a.uviaI plain formation

14. Thanks to wind and water, the products of one place's weathering become materials for another place's _

A. {omtnKtlvt forces

A. voIcarKll'i

B. destructivt forces C. surface ieatUfes D. land buildup

8. glaciallitl C. corill reek O. deposition

(hapter 6

Inquiry Skills 15. Make a Model Suppose you have a lump of SlJgar. watet, a spray bottle, and a cake pan. DeSCIibe how you could use those items to construct a working model of erosion and dej)osition. 16. Infer The icy sidewalk in front of your school was treated with salt to help the ice melt. In the spring. you noticed the cement was numbly and fall ing apart. What type of weathering did you observe? Explain.

Map the Concept Complete the concept map using words wom the list below. Some words belong in lllOfe than one category. glaciers acids weatherin g erosion O..... trudiv. Forces

deposition pl ateau volca noes lava sediments co ntinental shelf SurfMe

Features

Constructive forces

17. Apply What features on the ocean floor are similar to features on Earth's suriace? 18. 5ynthesize Formations called stalacti tes and stalagmites grow in (aves where the water evapol"ates. A mineral deposit. calcium carbonate. is left behind. Describe anothet locatioo in nature where a similar process takes place. 19. Apply Look at the photograph of the meandeling river on page (25. Water flows at diflerem speeds through a meander. Whele do you think the water flows the fastest? Explain your reasoning. 20. Evaluate Two statues wete put up in the center of a busy industrial city. One is made from martJle and the Other is made from granite. Predict what the statues may look like 50 years from now, Explain you r reasoning.

Performance Assessment Draw a Map Illustrate four of the following terms with a drawing. You r drawing should accurately represent the main charactetistics of these features. continental

continental

continental rise

"'"

barrier island

"""

seamount

ocean

shoreline

mars/lfswamp

"""

~""

sand dune mid-ocean ridge

LESSON

1

Cool and crusty on the outside, hot on the inside- what is Earth's structure like? Read about it in Lesson 1.

LESSON Shaking earthquakes and erupting volcanoes- what forces of nature cause these dramatic events to occur? Read about them in lesson 2.

2 LESSON

3

Some mountains are

tall and jagged. Others are rounded and covered in trees. How do mountains form? Read about it in lesson 3.

Is Earth's Structure? Why It Matters ... Earth has a layered structure, wit h solid rock at the surface and partly liq uid rock material below. Understanding Earth's struct ure (an

hetp scientists predict when a geyser or volcano will erupt, or how a river will change courle over time.

PREPARE TO INVESTIGATE

Inquiry Skill Use Models When you use models, yo u study. make, or operate something that stands for a real-world process or action. Models can help you to understand bener or show how a process or action works.

Materials • modeling clay, 2 (olors • a small marble • metric measuring tape • aluminum foil

For step 4. review Using a Tape Measure on page H6.

A Model World Procedure

o e

Collaborate Working with a partner, roll modeling day into two balls of different colors. Make one the size of a golf ball and th e other the size of a baseball.

Use models The smaller day bClIl represents Earth's outer core. The marble represents its inner core. Push the marble into the

center of the smaller clay ball and reshape the clay around it. You now have a model

e o

of Earth's two-part core,

Observe The larger clay ball represents Eorth's mantle, Using the plastic knife, cut this clay ball in half. Reshape the clay so

that this ball can be wrapped around the two-part core. You now have a model of Earth's core and mantle. Measure Use a measuring tape to find the distance around your model at its "equator." Cut a rectangle of foil equal to that distance in length and one-third of that distance in width. Wrap the foil around the mantle and smooth it out. This thin layer of foil represents Earth's crust.

Conclusion 1.

Use Models In your Science Notebook, draw what your model of Earth would look like if you could slice it in half. Label the layers.

2.

Infer

How would you describe the layers that make up Earth's structure? Write about them in your Science Notebook.

Design an Experiment list some materials you could use to model Earth's layered structure. Describe how you would aJ'fange them.

Earth's Structure VOCABULARY

COre crust lithosphere mantle plate tectonics

p. ( 4\

~t rudure .

Its outer layer

p. (40 p. ( 4 \

p. {41 p.(42

REAOING SKILL

Tut Structure Outline

the text on this page using an outline form. Select key words and phrases as topic head ings.

H (

MAIN IDEA Earth ha~ a layered i~ "",de up of moving plate~.

)

Hot Inside In many parts of the world, columns of steaming hot wa ter can be found shooting up from Earth's surface. These boiling fountai ns are known as geysers. Geysers form in places where water drains down a decp channel in Earth's surface. At the bottom of the channel, hot rocks heat the water un til steam forms, pushing boiling water up on to the su rface. Finally, the built-up pressure forces the remaining water to erupt in a sudden explosion. The existence of geysers suggests that Earth is extremely hot inside. Yellowston(' National Par k in Wyoming is well known for its numerous geysers and hot spri ngs. Long before this region became a tourist attracti on, Jim Bridger explored its wonders. Bridger was a fur trader, scout, and moun ta in man. I-Ie told everyone he met abou t the many geysers and amazing sights of the region. Visit Yellowstone today, and you ...._ .... too can see evidence of Earth's hot interior. But just how hot is it inside Earth?

"Geysers spout up 70 feet, with a terrible hissing noise. at regular intervals. In this section are the great springs. so hot that meat is readily cooked in them .. .."

Ji m Bridger (1804- 1881) Geyser Ga~er

Yellowstone National Park's hot springs, geysers, and mud pots are evidence 01 Earth's hot interior. •

E

5.000

!

4,000

i f

Earth's temperature increases about 25' ( per km in the trust, then more gradually 1,0m the upper mantle to its cenler. ... Scientists cannot travel very far below Earth's surface to measure tempera tures directly. By studying mines and holes drilled in the crust, scientists know that the temperat ure increases abou t 2 to 3°e for every 0.1 km (300 ft) below the surface. However, the deepest drill holes reach less than 15 km (9 mil below the surface. So scien tists depend on other, less d ircct evidence. Scientists study geysers and volcanic activi ty to learn what Earth is like inside. They also conduct experiments on surface rocks and

Temperature of Earth's Interior

•

Earth's (enter

3.000 2.000

toOO

bf-t o~=::-=;-:-::;:-;-;;:;-,-;:;:;:-; 1,000 2,000 1,000 4,000 5.000 6,000 Depth (km)

minerals under conditions of high pressure and temperature. More information abou t Earth's interior can be gained by observing seismic waves. These waves are vibrations tha t travel through the solid Earth during earthqua kes. Seismic waves change as they travel deeper and as they move through different kinds of materials at differen t temperatu res.

~ TEXT STRUCTURE What information does the graph on this page present?

Earth', layers Earth has 3 layered structure. Most of these layers are made up of solid or pllTtly melted rock. The innermost hlyers ~re mostly II mixture of metals. ElHth's layers vary in thickness. The cr ust, Ihc uppermost layer, is much thinner than the other layers. The crust is nearly all solid rock. Under thc continents, the crust is mostl y granite and other light rocks.

/:,c, o, -. C",, : -pler 7 • lHSOft I

)

Below the oceans, the crust is mostly made of basalt-a diuk, dense rock. The crust is by f,lf the thinn est of Earth's layers. Under the continen ts. the ilvcTllge thickness of the cru st

is about 40 km (24 mil, but it may be liS much as 70 km (42 mil in mountainous region s. The crust is c\'en thinner under the oce.ms. The ocean-floor crust ha s a thickness of about 7 km (4 mil.

As discussed earlier, temperature increases as you go deeper into the Earth. So, the deeper that rocks are located, the hotter they are. The layer just below Earth's crust is the mantle. The mantle is about 2,900 km (1,800 m il thick and makes up more than two-thirds of Earth's m"ss. At the bound
Many scientists believe that the presence of molten iron "nd nickel in Earth's core explains why Earth is surrounded by a m"gne tic field. Acco rding to one theory, convection currents move slowly throughout the liquid outer core. Electric currents are produced as Earth rotates, setting up E
f)

TEll STRUCTURE

Use an outline form to organize the information about Earth 's layered structure.

When a peach is used as a model of Earth, what does the peach pit represent? (41

Moving Plates Have you e\'ff wondered if Earth's surface always looked as it docs today? Alfred Wegener wondered . . Wegener was a German meteorologIst and geologist. In 1915, he suggested that the continents were moving very slowly across Earth's surface. Known as the theory of continental drift, Wegener's ideas were based on evidence that included fossils and rock formations. However, he could not explain how the continents could mO\'e through the solid crust of the sea noor or what force could move them. So, his theory was rejected by most scientists. In the 1950s, scien tists discovered that molten rock from the rn.lntle was rising to Earth's surface in the ocean basins. As this rock cooled and hardened, it was being added to E..lrth's crust.

This discovery led scientists to suggest that the lithosphere is not one solid shell of rock. In fact, they now believe that the lithosphere is broken up into giant slabs of rock called plates. These plates seem to "no.lt" on top of the mantle, much like giant ships noating on a sea of thick molten rock. The idea of giant plates of rock moving slowly across Earth's surface is called plate tectonics. As you might expect, the plates move very slowly. Their a\'erage speed is about 10 cm (4 in.) a year. However, over millions of years, plates ca n mO\'e thOUs.lnds of kilometers. Then' are two kinds of plates. Oceanic plates consist almost en tirely of dense ocean-noor material. Con tinental plates are made up of lighter continental rock "riding" on top of denser rock.

This map shows Earth's major platts. Plates interact along their boUndari:" :.' ':...-- - -..----:;;;;;

Alrkan

1 • Lesson 1

Plal~

Pla tes interact at their edges, or plate boundaries. The pic tures show the interaction th.lttakes place at each type of boundary. At converging boundaries, two pla tes converge, or move toward each other. Eventually they collide. When plates collide, one may ride up over the other. The upper plate forces the edge of the lower plate under the surface. This is called subducti on. Subduction usually occu rs w hen a con ti nen tal pla te and an oceanic plate converge. The dense rock of the oceanic pla te slides under the ligh ter roc k of the con tinental pla te. At divergi ng boundaries, two pla tes move away, or diverge, from each other. Molten rock rises up in the gap between the plates, forming new crust. Th is usu~l1y h
Converging Boundaries Two ptates mOve toward each other. One ptate may move under the other in a process called subduction.

Diverging Boundaries Two pl~tes move ~way from each other. Molten rock rises to fill the g~p, (feating new (fltSt.

Sliding Boundaries Two plates slide past each other, moving in opposite directions.

.. A fossil of a tropical fern like the one shown below was found here. Since the fossil formed. the region is believe-d to have moved 3.200 km (2,000 mil on a section of a continental pla te.

Evidence for Moving Plates Scientists conclude that Earth's plates have been moving for at least two billion years. They base this conclusion on evidence found in rocks at Earth's surface. These rocks have bem eroded and deposited since the planet first took shape. As you learned in Chapter 6. all rock at Earth's surface is subject to weathering and erosion. Weathered rock, or sediment, is deposited in layers. In turn, the layers eventually change into sedimen tary rocks. Layers of sedimentary roc ks provide clues to changes that were taking place at the time the layers were forming. For example, the layers can show the mineral content of the rocks and how the sediment was deposi ted. The layers may also contain fossils . A foss il is the physical remains or traces of a plant or animal that lived long ago. Fossils are usually found in layers of sedimentary rock. 7 • Lesson 1

By studying fossils in roc k layers, scientists can get an idea of how plates moved in Earth's past. For example, fossils of similar species have been discovered on opposite sides of an ocean along the edges of different con tinents. Scientists believe thai the fossils come from a period when those con tinents were joined. Over time, the continents separated, taking the fossils to new locations. Some fossils seem to be very far from where they were deposited. Fossils of tropical plants and animals have been found in polar regions. Fossils of fish have been found near the tops of mountains. Scientists believe that the fossils were carried to their present loca tions by the mOvement of tectonic plates.

1)i TEiT STRUCTURE

Use an outl ine form to organize information about the evidence support ing the idea of moving plates.

Review

o MAIN IDEA What parts of hrt" has a I~yered structure (onsisting of the crust, man tle, outer (ore, and inner (Ore.

a hard·boiled egg are used to model Earth's structure?

a Earth's VOCABULARY Wha t parts of structure combine to form the lithosphere?

f) READING SKilL: Text The nust and upper man tle make up the rigid lithosphere, which is broken in to large sections called plates.

Plates in teract in three ways at their boundaries: they may converge, diverge, Or slide p3st one 3nother.

fOSSils and other material in laye~ of rock provide evidence of Earth's moving pla tes.

Structure Outline the text under the head "Moving Plates" on page (42.

o CRITICAL THINKING: Apply ing At a converging boundary, why do ocean plates usually subduct beneath continental plates?

o INQUIRY SKILL: USe Models

Describe how you would use small rocks. pieces of board, ami a tub of water to model Earth's lithosphere.

.eTEST PREP The thinnest layer of Earth's structure is me A. crust.

B, lithosphere.

C. IIlner core.

MATH

Cal culate Diameter Earth's inner and outer (Ore (Ombined are about the size of Mars. Using the measurements on p~ (41, calculate the diametel of Mars in kilometers.

ART

Build a Sculpture Build a movable sculpture that models one or more plate boundaries. Use modeling clay, fabric, or other available materials. Write a paragraph that explains what the model shows.

D. mantle.

~ Technology ,.... Visit w_.edupla(e ,comls(pl to lirld oot more ~I>oot E~nh'~ ~lru(!ure.

Readers' Theater

Alfred Wegener and Pangaea What is Pangaea? Scientist Alfred Wegener

(1880-1930) believed that long ago the seven continents were joined together, forming a supercontinent he called Pangaea.

Characters Alfred Wegener

The Seven Continents:

AI,;,,,, Antar(1:ica, Asia,

Aust.alia, Europe. North Americ.a, SO\Ilh AlMrica

READING Tlll'stttiug is plauet Earlll, amI Wegml'T is IlIkiug tl,f slllge.

Wegener (to lIudience); Good afternoon, [am German scientist Alfred Wegener. £urope (aside): His name is pronounced ~VAY-guh-ner.~ Wegener: My friends and I are here to present my theory of continental drift, which [ published in the year 1915. North America (shocked): Did you say "continental drift?" Are you suggesting that continents move? Wegener: Don't act so surprised! Surely you know It",1 (\)l1til1~'l1ts mo\'", during earthquakes and volcanic eruptions, North America: Yes, butWegener (lro/dillg lip Ollt /"!IId at North AIIIl'Tira): Let me tell you my story. Then you will understand, It all started when I was a young man fascinated by maps, One day I noticed that the Co..1Sts of two continents appear to fit together, like pieces of a jigsaw puzzle, Africa and South America, will you demonstrate? Africa (Ifloving toward $ol/Ih Amtrica); If I tum a little this way, and South America rotates that way. , , South America: Yes, we couid fit together, couldn't we?

Wegener: Yes! That got me th inking, I found out that nearly identical fossils have been discovered on both sides of the Atlan tic Ocean, as well as iden tical rock layers, There are similar pairs of mountain ranges, too, such as the Scottish Highlands in Europe and the Appalachians in North America, Asia: What are you driving at? Are you s.,ying that some of the continents were once joined together? Wegener: Not SOIflI' of the continentsall of the continents! That's my theory, Antarctica: Incredible! Wegener: Isn't it? I caU this )ained continent Pallgaetl. That's Greek for "all the Earth," Might the seven of you demonstrate what Pangaea looked like? Wegl'lll'r 1I'IJVf!i dimliolls, TIll' co/rlium ts 1fl0Vt togl'llrtr to jomr Pangaea,

Australia (strmrblillg): This is terribly disorienting, Am [still Down Under? South America: Hey, somrone's stepping on my Galapagos Islands! Antarctica: It's getting a bit too warm around here. Wegener: Stop right there! Perfect! As you can see, the continents fit together into one supercontinent. According to my theory, this is how E"rth looked about 200 million years ago.

Continental Drift

.. 225 mill ion yea rs a9"

Africa: So anim~ls could w~nder from me to South America, is that right? South America: Plan t seeds could travel easily, too. Wegener: Right and right. But over the years, slowly bu t surely, the continents drifted llpart. Wegller gestures at tile colltillmts . Tiley drift apart, /xIck to tlleir modem-day I'CSitia.IS.

Australia: Well, it was fun while it lllstcd! Europe (10 tile OIlINS): Maybe ]'11 see you again in another 200 million years or so. Wegener: Perhaps, perhaps. My theory about Pangaea explains a grellt deal about Earth's geogrlIphy. For example, have you noticed tha t moun tain ranges are found mostly near the edges of continents? ( (48 • Cha pter 7 • l esson 1

)

200 mill ion years ago

South America: Now that you mention it,] hllve a rugged mountain range running along my west coast. North America: Thlll's funny, so dO ]1 Asia: And I have the Himalayas, that tall mountain range just north of India. Wegener: According to my theory, mountains arise when continents move in to each other. For example, the Himalayas rose when India slammed in to the rest of Asia. Asia: Ouch! North America: Well, Mr. Wegener, you seem to have solved all the mysteries of our plMe t. So tell us: Just how did con tinents move around the planet? Wegener (slmking Ilis l/ead): Well, you've hit upon the weakness of my theory. [could only guess ll t how the continents moved. Many of my critics enjoyed poin ting this out.

.. P'e5en t D,ly

100 million yU'5 890 COl/li/JiUIS go/her orolilld Wtgt'uer olld

1/a1 hilll 011 tI", bock ill cOllso/llticm.

Wegener: It's okay. After my time, people decided that I was correct. You see, scientists began stud ying the ocean floor. Asia: Wha t do oceans have to do with anything? Wegener: A great de.li! Scientists ha\'e discovered gian t mountain chains, called mid--ocean ridges, in the ocean's depths. In these ridges, molten rocks ri se from below Earth's surface and become part of the ocean floor. Europe: So what does that mean? Wegener: [t means that the ocean floors are mov ing. tool Oceans and continents move in giant sla bs that scientists cal! tectoni c plates. Jf I"d lived long enough, 1 would have studied tectonic plates myself.

Australia: I"d like to than k Mr. Wegener for proposing new ideas that challenged old ones. That's \'ery importan t in science! Africa: Plus, he used evidence from many different branches of science. North America: A keen observer and a logical thinker- thrlt's our Mr. Wegener! Wegener: Why thank you, my friend s. [am truly-moved! AIIIIII/gh.

Sharing Ideas l READING OIECK What is wegeltef's theory 01 oonunenta[ driftl

1. WRITE ABOUT IT Describe facts about Earth's geography that wegener's theory explains.

1 TALK ABOUrIT What lessons about science does Wegener's story illustrate?

What Are Earthquakes and Volcanoes? Why It Matters ...

PREPARE TO INVESTIGATE

When a fruit pie bakes in an oven, juices and steam seep lip through cracks in the (fust. That is similar to how a volcano forms. Volcanic eruptions and earthquakes can be violent events. By learn ing more about the m, people may be able to avoid some of the dangers they represent.

Inquiry Skill Analyze Data When you analyze data, you look for patterns in information you (O llett. Those

patteros tan lead you to draw conclusions, make predictions, and state generalizations.

Materials • world atlas • blank world map • red pellCil

• green pencil

.. A volcanologist is a scientist who studies

volcanoes.

Picking a Pattern

{

Procedure

o

Compare Read and compare the lists of earthquake and volcano locations below. What similarities do you find? Eart.h'l.uakol.

lIoo ..... 50 .. hM 1o~"",,1a

,"....",1 , 01&0

,Yeae

-,-

_ _ ..

~od.

~&.., .......-

~r_",""" ow..

G

o

Yn,

'm ,~

~

-.........,... ,1(00_.... _ _ •

Ve>l,.~CHI.

~

,=

,~

,~

Use Models Use
locations of the earthquakes and volcanoes. Record Data Mark each location on the

blank world map. Draw a red triangle for a volcano. Draw a green circle f or an earthquake. Check your work.

Conclusion 1. 2.

,-

Science Notebook, draw condusions about the pattern you see. Analyze Data In your

Predict Using what you know about Earth's structure, predict the relationship between the planet's plates and the places where most volcanoes Clnd earthquClkes occur.

Investigate More! Reseall:h Use tile Internet or other reference sources

to research a rKefit maiO!' earthql)(lke or volcanic efUption. Where did it take place? WIlat damage did it cause? Report your findi~

vat" b~ Reading VOCABULARY (';lrthquake epicenter fault fO(us magma

$eismi< waves

Earthquakes and Volcanoes

,,"

"" ""

MAIN IDEA Earthquakes and volcanoes change Earth's

p. (52

surface. usually al plate boundaries.

p. (56 p.tS)

Atthe Faults

•• • Cause and Effect Track the : •

READING SKILL

general causes and effects of : faulting.

DOD

: •••

••• ••

As you have learned. Ea rth's (rust moves very slow ly. Typically, this motion can hardly be felt. But at times, il can cause sudden and unexpe<:ted changes to Earth's su rface. Most major surface changes occur a t or near plate boundaries. Reca ll from the last lesson that plates may push together (converge), move apart (diverge), or slide past each o ther at plate boundaries. Faults are cracks in Earth's crust along w hich movement takes p lace. AI a fau lt, rocks often bend

and fold . Sometimes, they lock together and jam along the fault. Over many years, stress builds up on the rocks as the plates strain against each other. Finally, the rocks brea k. The plates shudder and jolt in to a new position. This sudden movement causes Earth's crust to shake. The wavy lines from a seismograph indicate the strength of seismic waves moving through Earth's o ust. T

Different Kinds of Faults As the crust shakes, it sends out shock waves of energy known as seismic waves. A seismograph has sensors that dete< t and measure vibrations of Earth's crust. The seismograph produces a record of seismic waves called a seismogram. The movement of rocks along a faul t is called faulting. During faulting, the rocks crac k or split into blocks. The blocks then continue to move in relation to each other, sometimes leading to further faul ting. The drawings show the three main types of faults. Each is caused by a different type of force applied in the region where movement takes place. At diverging bound aries. the force stretches rock. Eventually the rock brea ks and one block moves down illong il ~Ioping crilck. Mid-occ,m ridges are typicill lociltions for these types of faults. Other faulls occur at converging boundaries. Here, the force squeezes rock. When Ihe rock brea ks, one block moves up along a sloping crack while the other moves down. Often this occurs in regions of subduction, where one plate plunges below the other. The third type of fault occurs in regions where blocks move horizontally past each other. These faults are common at sliding boundaries, such as the 5.ln Andreas Fault in California.

~ CAUSf AND HFfCT What Ilappe ns wilen stre ss bui ld s up a lo ng a fault?

Fault at Diverging Boundary As sect ions of the crust move apart. rocks are stretched until tiler snap. causin g one block to move down along a sloping cra< k.

fault at Converging Boundary RlKks are comp. esse-d as they come togethe., caUSi ng one block to mOve up along a sloping crad as the other mOveS down.

Fault at Sliding Boundary RlK ks gri nd agai nst each othe r as they move ho.izontally past each other in opposite dircct ions. Pressure builds up al ong the fault until th e rocks break .

... The city of Taipei in Taiwan suffered a devastating earthquake on September 21 , 1m.

Earthquakes An . arthquak. is a violent shaking of Earth's crust. The releasc of built-u p energy along a fault is what makes E..1rth shake, or quake. The energy released depends on how much rock breaks and how far the blocks of rock shift. With the records produced by seismographs, scientists can measure an earthq uake's energy. This measurement expresses its size, or magni tu de, using a scale called the Richter scale. For exam ple, an earthquake with a magni tude of less than 35 may not even be felt, although it is recorded by the seismograph. An earthq uake measuring 7.5 is a major earthquake. The surface effects, or intensity, of an earthquake vary from place to CS4 • Chapler 1 • lesson 2

place. Intensity is measured by what can be seen and felt on the surface. What people see and feel often depends on how far they are from the earthquake's focus. The fows of an earthqu ake is th e point underground where the faul ti ng occurs. Most focus points are less than n km (45 mil below E.."\rth's surface. The point on the surface directly above the focus is an earthquake's epice nter. Tha t is where the intensi ty is strongest. Why? The epicenter is the closest point to the focus, where seismic waves are strongest. The shaking is caused by the energy of the seismic waves. Long after the initial earthquake occurs, continued seismic wave activity can cause mini qua kes, or aftershocks.

o

Shaking is most violen t at the epicenter 01 an ear thquake, directly above the focus.

o

seismic

Wil'lft

~ead O
10cU$,

Irom the

de-crusing

in energy as they travel.

There are two general types of seismic waves-body waves and surface waves. Waves that travel through Earth's interior arc called body waves. The deeper they extend, the faster they traveL Body waves called P waves can tr<welthrough Earth's interior in less than 1m hour. They can pass through solid and liquids. As P waves pass into and out of the liquid outer core, they change direction. They return to Earth's surface, where they cause b.lck-and-forth motions of rock. Body waves called 5 waves travel slightly slower than P wavcs. When 5 waves reach the surface, they cause it to move up and down. However, 5 waves can travel only through solids. So, S waves that pass from the mllntle into the liquid outer core lose their energy and do not return to the surface.

Surface waves, or L waves, travel along E.lrth's surface. These waves travel more slowly than body waves. Surfnce waves do not travel too far from the epicenter of an earthquake. However, surface waves cause the most damage, because they make the ground swell and roll like ocean waves. The damage caused by surface wavcs can be ex tensive. Buildings fall down and roads heave up. Bridges collapse. Glass breaks. Rivers change course or flood their banks. Trees topple and cliffs crumble. Qut at sea, massive waves are set in motion. These waves, often 30 m high (90 ft), can reach spccds of 500 km/h (300 mi/h). Such waves can cause great amounts of damage when they crash on5hore.

~ CAUSE AND EFfECT Why do ~urlace waves

cau~e

conne
",=11

great damage?

T

--

5'_ IMIt

lLJ - . , . ~ .... 101 ~ -,,~

I£:!I .... " ' . - .. ~

.... 011_

Volcanoes A \'olcano is an opening in Earth's surfact' th rough which mel ted rock, hot gases, rock fragments, and ash burst forth, or erupt. A violent eruption can release rivers of red-hot molten roc k, hissing jets of poisonous gas, curling douds of thick gray ash, and explosions of scorched rock. You can see why \'olcanoes an! sometimes n!ferred to as mountains of fire. In fact, the word volcallO comes from the ancient Roman god of fire, Vulcan. How do such mountains of fire form ? Volcanoes come from Earth's hot interior. Most volca noes start 37 to 100 miles below the surface. At these depths, rock can become so hoi it melts. Melted rock below Earth's su rf.lce is Cil\led magma. When rock melts, it releases gases. These gases mix wi th the magma, making it lighter than the solid rock arou nd it. Slowly, the gas-filled magma rises toward the surfact'. As it rises, it mel ts rock around it, gradually forming a large chamber. This chamber may be only a few kilometers below the surface. Under pressure from the weight of surrou nding rock, the magma is forced to find an escape. [t melts or forces a channel into weak or cracked rock. Within this channel, it pushes upward. Once near the surface, gas and magma bu rst through a central opening, or vent. The erupting material builds up, forming a volcanic mountain, or volcan o . • lessoo 2

After an eruption, a \'olcano usually collapses into a bowl-shaped mouth called a cra ter. At the bottom of the crater lies the ct'ntral \'ent. Many volcanoes have repeated ("ruptions. In these later ("ruptions, some of the volcanic mat("rial in the channel may remain below the surface. It may also push out through side \·enls.

Lava flows Volcanoes have been catted mountains of fire.

o

HoI, 9"~·fill ~d magma ri~es, melting rO(k along th~ way. until it form~ a
Three main types of volca nic ma terial are ejected during an eruption. The mllin one, mllgmll, is called lava once it reaches the surface. It may be fast-flowing and liquid·like or thick and slow-flowi ng. As it comes from a volcano, flowing lava may be hotter than I,HXFC (2,0Cl0°F). As it cools, lava hMdens into forma tions such as boulders, domes, cones, tubes, and smooth or jagged sheets. Roc k fragmen ts may form when gas in sticky magm a canno t escape. Pressure builds up untillhe gas blasts the magma apart. The fragmen ts erupt into dust, ash, and large chun ks call ed bombs. Small bombs, called cinders, may be no larger than a baseball. The largest bombs can be more than I m (3 ft) wide and weigh 100 tons! Gases are also released d uring a volcanic erupti on. Mostl y steam,

o

Prn~ure buitd~ until the g~~ and magm~ force open a (hannell~ading to the ~urfact. Volcanic material moves through this channel and erupts through th~ v~nt.

volcanic gases often con ta in poisonous chemicals. These gases mix with IIsh to form a deadly blllck smoke. There are different classes of volcanoes and volcan ic cones. Shield vo lcanoes form when a lot of lava flows smoothly from a vent and spread s out to cover a wide area. This ac tion creates a broad , low, domeshaped volcano. Cinder cones form when mos tl y rock fragments erupt and are deposi ted around the ven t. This crea tes a coneshaped volcano with steep sides. Composi te volcanoes are also cone shaped. The sides of these volcanoes are steeper than those of a shield cone, but no t as steep as a cinder cone.

~ CAUSE ANO EffECT What c.luses magma to

ri s~

t o the surface?

North

A large number of volcanoes lind earthquakes strike /llong tile edge of the Padfic Ocean. This explains why this zone is (ailed the Ring of Fire. •

Ring ofFir. Many earthqu akes and \'olcanoes occur in a zone that borders the Pacific Ocean. For that reason, this wne has ~n named the Ring of Fire. The Ring of Fire outlines Earth's subduction 7.ones, places where one of Earth's plates is forced under another. ll"Ic Pacific Plate converges with several continental plates to form the Ring of Fire. Faulting during su bduction cauSC'S earthquakes and can also lead to \'olcanic acti\'ity. As the subducti ng plate sinks into the mantle, it melts to form magma. The magma may later rise to the surface as a line of volcanoes. (58 • Chapter 7 • l esson 2

On the ocean noor, a deep narrow valley called an ocean trench may form along a subduction 7.One. Resulting volcanoes often parallel the trench, usually in an arc. Faulting at diverging boundllTies also causes earthquakes and creates volcanoes. Diverging boundaries are usually located nellr Ihe middle of ocean basi ns. At these boundaries, magma rises 10 Ihe surface between separating plates, creating \'olcanic mounlain ranges known as ocean ridges. Faulting at the ridges I('llds 10 ea rthquakes.

1;)

UUSE AND uno

the Pacific rim a region of earthquakes and active volcanoes? Why is

Review

o MAIN IDEA Why do earthquakes and volcanoes usually occur at plate boundaries?

An urthquake i~ a vio len t ~haking of (arth'~ < ru~t (au~ed

by

faulting. which shif~ rock and sends out seismic waves. Volcanoes form when gas·filled magm a rise'S through Earth's interior. Thi~ forces volcanic material~ to bu..;t through a vent. Many volcall(les and earthquakes occur in a subduction lone around the Pacific Ocean called the Ring of fire.

MATH

a VOCABULARY Define epicenter and focus and describe their relationship.

e READING SKill..: Cause and

Effect Describe the cause-and· effect relatiO!lship that creates yolcanoes in the Ring of fire.

o CRITICAL THINKING: Analyze How would Earth be different if i~ crust did not move and it lacked tectonic plates?

4) tNQUtRY SKILL: Analyze Data Research at least fi~e recen t earthquakes or yolcanic eruptions. Add them to the list on Page C51. Do the additional data support the conclusions that this lesson presents about earthquakes and yolcanoes?

~ TEST PREP

Make a Graph Research three recent earthquakes. Make a bar graph that shows the Richter scale readings for each earthquake. Share your graph with the class.

Seismic waves that cause the most damage are A. P wa~es. B. surface waves.

TECHNOLOGY

Prepare a Report How can old buildings be rein forced to withstand earthquakes? Research this question on the Internet or at the library. Write a report to present your findings,

C. ocean waves. O. body waves.

I-t

Technology

.... \/isit www.edupt.ce.comlscplto find oot more aboott!>e most famous YIlIcani< erup~ons in re
How Do Mountains Form? Why It Matters ... Have you ever wondered

why mountains often form along a (oastline? Or why those

mountains look like wrinkled land? Understanding how mountai ns form allows people to und erstand what

Earth's surface was like in the past. It also helps them predict future changes in Earth's surface.

PREPARE TO INVESTIGATE

Inquiry Skill Observe When you observe,

you use your senses to accurately describe things, making sure to distinguish between fact s and opinions

or guesses.

Materials •

shoebo~

lid • ITl(list sand

• scissors • wax paper

• ~asurjn9 cup goggles

,:-::-:,--------,

Science and Math Toolbox

For step 2, review Ml!asurem~mt on page H16.

Make a Mountain! Procedure Safety: Be careful when using scissors, Wear goggles for this investigation.

€I Collaborate Work with a partner. Place a shoebox lid upside down on a flat surface.

e e

Then carefully cut a narrow slit along one end of the lid where it bends up.

Measure Line the top of the lid with wax paper. It should be the width of the slit and about 2.5 em (1 in) longer than the

lid.

Use Models Place the wax paper in the lid. Pull one end of the paper about 2.5 em (1 in) through the slit. Spread half of the

sand CIt the end of the lid near the slit.

<)

Use Models Spread the other half near the center of t he lid, Each pile of sand

represents the crust on one of Earth's plates. Draw the model setup in your

e

Science Notebook.

Use Models Slowly pull the wax paper through the slit to model the movement of one of Earth's plates.

Conclusion

Inve'Stigate More!

1.

Design an Experiment Select matefials to model what happens along a divetging boundary.

Observe In your Science Notebook, draw what happened to the sand as accurately as you can,

2.

Compare How does what happened to the sand compare to what happens to rocks in the crust when two plates collide?

vat" by Reading VOCABULARY dome mountains

p. (64

MAIN IDEA Mountains are f ormed by various processes, usually al plate boundaries. They can be classified by Ilow

fault-block

p. (63

they form and by their height

mountains fold mountains

p. (62

Folding and Faulting Forces

READING SKILL

ClitegorizelClanify Use

II cllart to list the types of mountains and the forces that bui ld them.

Awesome! That is wh", you might think as you look dow n from a high mountain pea k o r gaze at mountains along a horizon. lndct'd, moun ta ins are awe-inspiring. Not only are they Earth's highest surface features, bUllhey are some of its most

beau tiful. From the Alps in Central Europe to the Rockies in North America, mountains ma ke up the backdrop to many of the world's scenic spots. G rand in scale and g reat in mass, mountai ns may seem permanent. However, li ke E.1rth's other surface featu res, they are continually being created and destroyed . Most moun ta ins form at or ncar pta te boundaries. In fact, most of the largest mountain ranges form where two plates collide and force layers of roc k into folds. These are known as fold mountains. The Andes shown below are examples.

-

Folding folding often occurs at the edge of a continen t and results in long, narrow moun tain ranges, such as the Andes along South America's west coast.

Faulting Fau lting can produce drama tic cliffs when a large seelion of rock is forced upward or downward, as in this formation in the Rocky Mountains.

Fold mountains of len form where an oceanic plate collides wi th a con tinentill plil!e. Sediment from the oceiln floor be.:.:omes altilched to the edge of the continen t. The sediment and con tinental roc k crumple together, crea ting rolling folds. As the layers of roc k wrink le, they may also crack. This creates faults, or fractures, in the crus t. Erosion softens the folds over time. For that reason, some of the oldest fold mountains, like Arkans..1S'S Ouachita Mountains, have rounded pe
Most f
~ (LASSIFY

Which type of mountilin is usu.. lly formed at (Onverging bound .. ries?

Volcanic Forces Sometimes volcanic acti vity fonns mountains. This type of mountain usually forms at pl~te boundaries. Volcanic activity may happen at converging boundaries when the edge of one plate sinks beneath another and melts into magma. If the magma rises and bursts through the crust, it generally forms a volcanic mountain. This process may even happen within moun ta ins formed by o ther processes. For example, many of the mountdins in the Andes chain in South America are volcanoes. At diverging boundaries, magma rises up in the gap between the two plates. It then cools on the surfa ce into ri dges of new platC' 1T41tC'rial. Recall that mid-ocean ridges form on the ocean floor at dh"erglng boundaries. Thes(' underwater mountains make up the world's longes t mountain chain. Volcanic mountai ns can form away from plate boundaries as well. Magma plumes rising in the

mantle create hot spots in the crust. As a plate moves over a hot spot, \'olcanic material erupts through the plate, creating a chain of volcanic mountains. Sometimcs magma rises towa rd the surface but d oesn't break through the crust. It may push up under Earth's crust, creating a domeshaped mound. The molten rock th en cools and hilrdens. This is how dome mountains are formed. Erosion often continues to shape domC' mountains. Irregular peaks and valleys may result. The Black Hills in South Dakota and the Adirondack Mountains in New York are examples of dome mountains. Some mountains are formed entirely by erosion. ThC' Catskills in New York are an example. These mnllnlll;n<; fnrml'<1 w h"n "!"Minn

carved out peaks and \'allcys from a platea u. (USSIf'f

How are dome mountains different from other mounldinsl

Dome Dome mountains form when YOlcanic material bulges upward unde. the crust, ha.dening as it cools. A number of dome moonlains 1If! to the east of the Rocky Mountain range.

Review

o MAIN IDEA Name and describe

Visual Summary (

Mountain Formation

the four types. or classes. of mountains.

I

Fold Mount.in,

a VOCABULARY How does a dome mountain form?

9 READING SKilL: Categorizel Classify Which two types of mountains are formed by volcanic activity?

o CRITICAL THINKING: VOl",,";,; Mountain,

Synlhesizing What might you conclude if you I1
o INQUIRY SKILL: Observe Dotnf M"""taiM

If someone described a dome moun tain as "beautiful: would that be an accurate scientific obse!vation? Why or why not?

.tIEST PREP Which of these is not a type of mountain?

MATH

(onvert Units One of the highest mountains in the Alps is Mont Blanc, which is 4,810 m high. How many kilometers is that?

B. lold

WRITING

D. diverging

Write a Story The Navajo in the southwestern United States honor the mountains that surround them. Tibetans honor the Himalayan peak Kang Rimpoche. Choose a culture that lives near mountains and research their beliefs about mountains. Write a story about the people and their mountains.

A. fault-blad

C. dome

~ Technology 'iii. Visit w_.edupla
SLEEPING GIANT Talk about waking up on the wrong side of the bed! Snowcapped Mount St. Helens slept for iii hundred years. Then on May 18, 1980,

the volcano blew its top in one of the gr.atest explosions in recorded history. The sideways blast blew down enough trees to build 300,000 homes. Debris from the volcano was 600 fHt dHP and even blocked nearby rivenl Befor. the eruption, the mountain was 9.677 feet taU. Afterward it was 1,314 feet shorterl Recently, the volcano has shown new signs of activity. Scientists are monitoring it closely to determine if another major eruption will occur. In 1980. plumes of lIsIl reached a heigh! of 80,000 leet. .... blocking air traffic. In three days. the ash traveled all

the way across the UnilO!'d States.

(66 •

READING

: Compare and Contrast

The View From Inside This picture is taken from

inside the blol-'m-out top of Mount St. Halens. Here

you can see the in"er w.ll .. of the volcano'. cone . ...

, ,..:I'

• • Danger Mounting This rising. steaming lump Is called a lall8 dome. As magma pushes up from underneath It rises higher and higher-until the nallt big eruption. When will it be?

•

..

,.

. 1'I:lI"

..

",

>.

.

. . ..

.-....

Vocabulary Com plete each se ntence wi t h a term from the list. 1. The ootermost ~ of Earth is (ailed the _

(0«:

2. Tho __ is ~ 01 the solid upper mantle and the CMt. 3. Tho _

01 iK1 earthquake is the point undergrotnl ~e laulting OCCUl'S..

4. The layer 01 Earth between the (JUst and the ooter (Ofe is called

""-

5. Shock waves of _gy released in an earthquake are called __ 6. The re~ase of _gy along a faul t causes an _

1. Earth's innermost layer is the _ 8. Molten rock, Of _

that lIows on the surface is called lavil.

9. A crad in the oust along which rocks move is ca ll ed a __

( 4t

trust (40 dome mount.ins (64

earthquake (S4 epi(~ter CS4 fault (51 fault·bloc:k mountains (63 fO(us (S4

fold mountains (62 lithosphere C41 magma CS6 m.... tle (4' seismic waVH C53

10. __ form when magma pushes up from benea th Earth's crust.

~ Test Prep

Write the letter of the best answer choke. 11 . Earth's rigid outer layers are bfoken up into _ A. divtr9ing boundaries B. tectonic: plates C. tIN! (JUSt and the lIII'KKp/Ifte D. 1M inMr and OllIei' tort

12. What instJUml'f1t measures the strength of iK1

Earthquake?

A. Tt.e1""'ne'leI'

B. AnemomM!I' C. Sping xait D. seMlograph

(68 • Chilpter 7

13. The temperilture of Earth·s inlerior _ A. increases with depth B. dKreases with depth C. is the SiIITIe throughout D. is I\9Il'St near the eqlJalor

14. Where does most mount.lin formation take place? A. at diverging boundaries 8. at .wd«ean ridges C. along ocean tr~ D. at plate boundaries

Inquiry Skills 15. Use Models What ~ind of faul t is shown here? Describe wflat is happening.

11. Apply The Himalaya Mountains lie on the northern border of India, which is also a plate boundary. Use plate tectonic theory to explain why MI. Everest is increasing in height. Wh at types of mountains are the Himalayas?

18. 5ynthesize As Alfred Wegenef

16. Analyze Data Describe the information that the Richter scale indicates about an earthquake.

Map the Concept

hypothesiled, Pangaea was a supercontinent tha t ran north to south across the equatOf. North America was positioned over the equator. How might the climate of the United States have been different from today? What was the climate like in Antarctica?

19. Apply Why r:io tall mountains form at mnvef!Jin!J and diV
20. Synthesizing During a strong earthquake. is the most damage done at the epicenter? Explain.

Complete the concept map using the words listed beJow. converging Earth core mantle sliding diverging

Performance Assessment Make Mountains

1

(

I

--JI~~

Create a po5ter diagramming the three different types of mountains. lrn:lica te the type of plate boundary, the type of mountain, and an example of wflere they O{(ur.

L-(

(

----'[' --'I

r(

' o
pI~'o.

1 1 ,)(r-..L.. -'1

r(_ _

LESSON

1

Cars, planes, and trucks- where do people get the energy to power vehicles? Read about it in lesson 1.

LESSON

2

Every day, wind and

rain carry away soil. What problems can soil loss cause?

Read about it in lesson 2. LESSON

3

Reduce, reuse, recycle- how can you conserve Earth's valuable resources? Read about it in lesson 3.

How Do People Use Resources? Why It Matters ... You depend on natural resources

for almost every activity of your life. Some resources. like the petroleum used to make gasoline, exist in limited supplies. When they afe used up, they are gone forever. If people use resources wisely, everyone will have them for yean to (orne.

PREPARE TO INVESTlGATE

Inquiry Skill Use Models When you use models. yo u can see what happens in a real-world

process.

Materials • 3 plastic cups ' M"" • measuril19 cup

• teaspoon • tablespoon • goggles • marking pen

Saen(e and Math Toolbox For step 3, review Measuring Volume OIl page H7 .

•

.

~

Just a Spoonful Procedure Safety: Wear goggles for this activity.

o

Collaborate Work with a partner. label one cup NNatural Resource. Fill thi s cup with 100 ml of sand. Label a second cup NResource Suppfy,H Fill it wi th 100 ml of sand. In your Science Notebook. make a N

chart like the one shown.

G

Use Models One partner will be the HreSOUfce user H a nd will use a tablespoon to remove sand from the Natura l Resource cup. Th e other will be the Hresource

supplier and use a teaspoon to add sand H

o o

to the cup. Spoon sand in and out of the cup at the same fate f or 30 seconds. Measure Measure and record the amount of sand re maining in the cup. Use Models Refill t he cup with 100 ml

of sand. Repeat rteps 2 and 3, but this time, only the resource user should spoon sand out of the cup. Do not add sand to the cup.

Conclusion 1. 2.

Compare What is the d ifference in the amo unt of sand in the Resou rce cu p for the two trials? Explain the difference. Hypothesize Based on the data, what do you think would happen in step 2 if both

students were using the same size spoons?

3.

Use Models What do the results show about natural resources?

.\

InveJtigate More!

r

Design an Experiment Repeat the activity, this time varyil"lQ the speeds that you add or remove the sand. How does changing the rate affect the final amount 01 sand in the cup 7 RepM )'OUr resurrs in a chari, graph. or diagram .

Earth's VOCABULARY (onservalion fossil fuel natural reso"rce nonrenewable resou"e renewable n'!source

p.C18 p,C1S p,C14 p,C1S p. (76

READING SKILL Prob lem an d Solution Use iii diagram like lhe one be low 10 compare po5~ble 5OIution5 10 the problem of limited natural re5OUr(es.

DO DO

Mining Copper (Omes from mines like the one here. Copper usually is found in combination with other elements. ~

8 • lesson 1

MAIN IDEA The Earth provides many resour(eS t hat people need and use. Some resour(eS are fou nd only in limited quan tities. Ot her resources are almost un limi ted.

Natural Resources The natural world provides everything that people need to stay alive, and many things that people find useful or helpfuL These resources indude air, water, minerals, and soiL They arc called natura l resou rces. Humans have found many ways to ta ke advan tage of na tural resources. We use them to build houses, grow crops, and raise livestock. We also use natur.ll resources as a source of fuel and electrical energy. Na tural resources that arc used to prodm;e energy arc called energy resources.

Nuggets Copper sometimes is found in pure nuggets like these. ~

Nonrenewable Resources

Pe troleum Formation

Some natural resources are not easily replaced. These resources are called nonrenewable resources. Once a nonrenewable resource is used up, natural processes take millions of years to replace it. Nonrenewable resources include oil, natural gas, and coal, which are examples of fossil fuels. They are called fossil fuels because they come from the remains of ancien t plants and animals. Oil, which is also called petroleum, formed from the remains of plants and animals that once lived in the oceans. How did plants and animals Change into oil? After they died, their remains settled on the ocean floor. Over time, sediments built up on top of the remains, which Wer"l!- pressed under the building weight of the sediments. This pressure, along with heat from Earth's interior, Changed the appearance and chemical makeup of the remains. Further pressure squeezed the remains into liquid. That liquid is oil. Other nonrenewable resources include minerals and some rocks, such as ores of aluminum, iron, and copper. These materials are used for building materials and for making a wide range of produc ts, from automobiles to jewelry. Because nonrenewable resources cannot be replaced, it is important to use them w isely. If people are not careful, these resources will not be available for future generations.

As marine plants and animals died, their remains were sometimes buried before tIIey completely decomposed.

Ove r millions of years, heat and pressure turned this organit matter into oil.

The oil collected in fractured rocks or in spaces between sediment particles. Today. oil pumps remove the oil from these spaces.

fJ PROBLEM AND SOLUTION

Why a re foss il fue ls e xa mp les of non re newable resources?

I

Renewable Resources Not all natura l resources are nonrenewable. Resources that are easily replaced or that can be used over and over again are called renewable resources. Farm crops and animals are examples. So are oxygen and fresh wa ter. Trees are renewable resources because new ones can always be grown. People use trees to ma ke paper products and for lumber. Wood from trees can also be burned as fuel. Many companies operate tree farms. For each tree that is cut down, a young tree is planted. Thus, the supply of trees is constantly renewed.

are a valuable natural re~our(e. By replacing cut-down trees. a tree farm can provide wood over and over again. T Tree~

Renewable resources that are used to produce energy are called alternative energy sources. They provide options to using fossil fuels. Wind Windmills have been used for hundreds of years to move water and to grind grain. Today, wind farms use rows of wind turbines to power electric generators. Like old-fashioned windmills, the turbines have blades that turn as the wind blows. The energy from the moving blades is converted into elec tricity. Solar Energy from the Sun is called solar energy. Solar panels can collect sunlight and convert it to thermal energy. This energy can be used to hea t homes. Other devices, called solar cells, convert the Sun's energy into electricity. Today, solar cells power calculntors and electronic road signs. In the fu ture, people mny be driv ing solar-powered cars! Water Power plants tha t use moving water to generate electricity are called hydroelectric plants. At these plan ts, water is held behind a dam and slowly released . The falling wa ter turns turbines, similar to the way wind turns turbines. The energy is converted in to electricity. Today, people still use fossil fuels for much of their energy needs. Yet these fuels are becoming scarcer and more expensive. Developing alterna tive energy resources makes sense for the future!

o

PROBHM AND SOLUTION

I'cople .educe their

u~e

of

How can fo~~il fuel~?

I

J

I

I

I

Wind In windy places. wind

w.bines tan generate ele
Cars powered by solar energy must have a large surface area

solar celis.. The solar celis collect the Sun's energy and convert it \0 electricity to power the car.

Hydroelectric plants use the force of moving wate, to turn turbines. The energy from the spinning turbines is converted into tle
C71

cars Hill on gasoline, a petroleum produd. As petroleum reserftS are used up, its (Ost is likely to rise e~n lIiglier. Mo~t

I!19S

2000

Conservation The efficient use of resources is c;llloo conservation. ConK>rving non renew;lble resoUTC('S is very importnnt, because they cannot be replaced. By not wasting fossil fuels, you can save them for the future. Another reason to COnK>f'Ve fossil fuels is to reduce pollution. Smoke from burning these fuels can mix with wilter in the ai r to form smog, which is not health)' to breathe. Blirning fuels ;ldds a gas called carbon dioxide to the atmosphere. This action mil)' be slowly warming Earth 's temperature, an en'nt called globalwanning. Scientists are studying this potential problem. Other waste gases from fossil fuels mix with wa ter in the air to form acid min, another environmental problem. Acid rain can kill trees and fi sh, and damage buildings and statues . • lesson

t

What might be the most important natural resource to consen'e? [n mlmy places, the answer is water. People need clean, fresh water for drinking, bathing, and growing crops. Although nature renews fresh water, the world's delThlnd for water increases every yea r as the population grows. You and you r family can help to conserve Earth's importa nt resoufCC"S by following some simple, common-sense practi ces. Use public transportation, or form carpools. Tum off electric lights and appliances when not in use. Fix leaky faucets. What other ideilS can you think of to prilctice COn5erviltion? "~oeUM

AHO SOLUTION

'Nhat problem (/In (onservation he lp to so lve7

Review

o MAIN IDEA Why is solar energy called a renewable resource? Natural

are if they cannot be r~placed in a person's li fetime. re'Sour(~s

nonr~newable

o VOCABULARY W. ite a short paragraph using the terms na/ural resource and energy

resource. f) READING SKill..: Problem and Solution Which alternative energy resource do you think is most likely to replace fossil fuels in the future?

Natural re'SOUrCeS are renewable if they can be quickly and naturally replaced.

o CRITICAL THINKING: Alternative energy SOurCeS help people to conserve fossil fltels, a nonrenewable resource.

Evaluate Where are the be-st pla<es to build wind farms? Explain your reasoning.

o INQUIRY SKILL: Use Models A student constructs

a natural resource using a can with a small hole in the bottom. With the hole plugged, the can is filled with salld. When the plll9 is removed. the sand drains out. What kind of resource does this model illustrate?

MATH

(reate a Graph Suppose a gasoline· powered car can travel 40 km (15 mil on a gallon of gasoline. A car that uses a combination of gasoline and electricity can travel 96 km (60 mil on a gallon 01 gasoline. Make a bar graph to show how far each car can travel on 25 gallons of gas.

~ TEST PREP Which of the following is a renewable resource?

A. oil B. natural gas

TECHNOLOGY

DrawaDiagram Research new technology that uses an alternative energy resource. Draw a diagram or illustration of the technology and present your display to the class.

a model of

C. lumber D. aluminum ~ Technology

lit

Visil www.eduplace.comlscpl tofiod 001 more about nalural .<'SOUrces.

Technology

In many ways. hybrid cars look and operate much like other modern cars. The difference is inside. Hybrids 3re powered by a combination of gasoline and electricity! As you read about hybrid cars, compare them t o conventional cars that run on gasoline only. What

adva ntages do you think hybrid carl provide?

-

Instruments This

~,,~

showJ the volume of gas in the tJnk and the (!large 01 th. ban. 'Y. T

-

Gasoline Engine

Electric Motor

The
than tM <'11ginH 01 most

Tilt mo lD. draws energy from tM ban trifJ to .«tle,ale lilt CaJ. Yet it also Cin iKt is i gent.ato<, 00119 tM tntrgy of the moving

can. II pollulH IHs. 100.

Q .

C<0 C8COC.--: o. '-pC"-'~8C.C,CH -W -"~'~)

10 rKlla,~ llIe battftin.

READING

When the ca.

Iravel~

On level surlacl'S,

When the ta. travels downhill, the mCllO.

uphill, the banery

the ca. uses one or

discha.QM to add extra power to the

both power sources, de pending Gn its

{onverU to an electric

car's engine.

speed.

the battery.

generator. It .ecM.ges

Gas Tank One popular brand of hybrid ca. {an travel more than 1,000 km (630 mil On a single tank (If gas.

Shari"qldeas I. READING (HECK How do batteries help a hybrid ca. use less gasoline? In a completely electric-powered ca., balleries take up a lot of the car's volume. Because a hybrid car needs 1M! battery power. its

balleries take up less spau.

2. WRITE ABOUT IT Des
3. TALK ABOUT IT How do hybrid cars compare to (a.s that run on gasoline only?

How Do People Use Soil? Why It Matters ... Plants need mature, nutrientrich soil in order to grow. Plants in turn protect and enrich soil. By studying how plants and soil interact, you can help protect both.

PREPARE TO INVESTIGATE

Inquiry Skill Observe When you observe,

you use what you (an see or measure t o help you draw a (onclusion.

Materials • 2 plastic bowls • meflsuring cup

• plastic wrap • goggles

• moist soil

Science and Math Toolbox For steps 2 to 4, r~jew Making a Chart to Organize Data on

page Hi t

A Mighty Wind!

Soil

S . mpl~

S.mpl~

Qu' lity

A

e

Procedure

~"

Safety: Wear goggles for this activity.

o

Collaborate Work with a partner. Place 250 mL (1 cup) of moist soil in each of the

two plastic bowls. Label the soil samples

e e

A and B. In your Science Notebook, create a chart like the one shown.

Observe Test the soil samples to determine their characteristics. For example, fee l

the consistency. dampness, and texture of the soil. Blow on it to see what effect wind might have on it. Record your observations. Expertment Securely cover soil sample A with plastic wrap. MClke sure there are

no holes or gaps in the wrap. Leave soil

sample B open. Place the two bins in a warm, sunny window and leave them

o

overnight. Observe Remove the plastic wrap from sample A. Repeat step 2 with both samples and record your observations.

Conclusion 1.

Compare Compare your data about the two soil samples. What similarities and differences do you notice? How do you explain them?

2.

Infer How do you think your observations might explain soil conditions in nature?

3.

Hypothesize Do you think that growing plants affect the way that soil holds water? How could you test your hypothesis?

Design an Experiment Will soil, sand. and gravel d~ out at different rales? Design an experiment to find out. Conduct the experiment with your teacher's approval.

v afn by Reading VOCABULARY

MAIN IDEA Soil supports the growth of (rOPS and o ther

re$idual soil

p. cas

soil soil profile subsoi l topsoil

p,C84

transported soil

Uses of Soil pl,mls. Soil must be protected because m"ture, nutrientrkh soil takes a long time t o form.

p,C86 p,C86

p,(86

p. cas

READING SKILL

Draw Con(lusions Use a chart to rKord you r conclusions about what conditions produce the best soil.

What is Soil? Soil is a natural resource that is made up of minerals and small roc ks, water, g ases, and org anic matter. The minerllls and small roc ks MC we1lthercd bedrock. The orga nic mat tcr, called humus, is decayed plan t and nnim,,[ materiaL Not all soils a re ali ke. Different geogra p hic areas have differen t types of soil. For example, the soil in a desert will be very different from soil in a forest. The type of soi l a p lace has depend s on several factors. These factors include climMe nnd the types o f rocks and organic matter present in the area. The s ize o f the particles in soil ma y describe the soil"s texture. Stud), the types of soil shown below. How d o you thin k the quality of soil affe<:ts the plants that grow in it?

Sandy Soil

Clay soil

Rocky soil

In sandy soil. particles are medium-sized and very hard. "

Clay soil is made up of very small. tightly-packed mineral particles. "

Rocky soil. or gravel. includes relatively large fragments of rock. "

8 • Lesson 2

How Soil Is Formed Soil forms in a process that ta kes thousands of years. This process begins wi th weathering. As you learned in Chapter 6, weathering is Ihe breaki ng down of rock into smaller pieces of rocks and minerals. If you were 10 dig a hole deep enough. you would hi t bedrock. Bedrock is unwea thered rock beneath the soil and other loose material on Earth's surface. As the upper part of the bedrock wea thers. it breaks in to smilller pieces. These pieces e\'entually become part of the mix ture called soil. Soil that forms from the bedrock beneath is called residual soil. Sometimes, the soil in an area has minerals that are different from those in the bedrock below. This soil, called transported soil, has been carried from some other location by wind and water.

b . thwo.ms, ~te.i" and fungi b.uk down dud plant and animal rnattl"ial. The remains

As soil forms, plilnts begin to grow. After plants and animals d ie, their remains decily. Rain carries the decayed organic milterial, or humus, from the surfilce in to the developing soi1. Humus adds nutrients to soil. Plilnt roots, insects, worms, and other organisms also help in the de\'elopment of nu trien t-rich soil. Roo ts grow into the soil, and insects and worms burrow in it. They create spaces between the soil particles. These spaces allow air to ci rculate and more humus to collect. How d~s t he ;;;;;;;; affect the type of soit in an al ea ?

Profile of Mature Soil Over time, as soil develops, defini te layers can be observed. These layers are called soil horizons. A ma ture soil has four horizons. Young

--

or imm1lture soil hilS fewer hor izons. All of the soil horizons together

•

are called a $oil pro fil e. In a ma ture soil profile, from the top down, the horizons are called topsoil, subsoil, parent material, and bedrock. The layers are also given let ter na mes, as shown in the diagram. Horizon A is the t opsoil. Topsoil

con tains h umus, minerals a nd rock fragments, as well as inse<: ts and earthworms. This part of the soil has the most nutrien ts and is important for growing plants. Most plant seeds germinate, or sproul, in topsoil. Horizon B is the subsoil. Subsoil usually contains very little hu m us. However, water washes down some nutrients and organiC ma tter from the topsoil. Some plant roots may reach d own in to the subsoil, and some earthworms and o ther organisms may be found here. The next layer, horizon C, is made up of chunks of partly weathered bedrock. This rock is sometimes called the parent material, be<:ause the soil comes from it. Below the parent material is the bedrock, or horizon D. This thick layer of rock is the founda tion for the soil.

The i 01 water, plants, and animals created the mature soil profile shown here . .. 8 • Lesson 2

~" DRAW (ONtLUStONS

What can you learn

from st udyi ng a soil profile7

Year 1

..." ..." ..."

Year 2

(anoia

(anoia

(o.n

Year 3

aa. ley

<".

(;",,,Ia

Vear 4

Flax

Vear 5

Soybean

Flax Batley

Alfalf.

These crops ale different from those that were grown in the same fields a season ago. A

.. This table shows several recommended crop rotation schedules for northeast North Dakota.

Protecting Topsoil As you have learned, topsoil is the layer of soil thai has the most nutrients. Plants use these nu trients in a way that is comparable to how ),our body uses vi tamins. While the nutrients are not food for plan ts, they are necessary for heal thy growth. The nu trients are passed on to anim als tha t cat the plan ts, and to animals tha t eat the plant-eaters. Organic material from these plants and animals then r('turns the nutrients to the soil. This cycle is important to all Jiving things. Farmers must meet the challenge of main taining nutrien ts in the soil. Growing crops ta ke nu trients out of the soil. When the crops are harvested, the nutrients are removed with them .

How do farmers solve this problem? One solution is to add fertilizer to the soil to replace the nu trients. This solution is nol perfect, however, because some of the fertilizer washes away when it rains. Another way of returning nu trients to the soil is through crop rotation. C rop rotation is the planting of different crops during different growing seasons. Each type of plant uses d ifferent sets of nutrients. If the s..1me crop is grown in the same field for many years, Ihe same nu trients arc removed from the soiL Wilh crop rotation, the soil is naturally repleniShed.

D DRAW CONClUSIONS

Acco.ding to the cha.t, if corn is g.own in iii field in Yeiilr ) , whiilt crop should be planted in Yea. 4?

Conserving Topsoil Fanners have found ways to prevent soil from losing nu trients. Howel'er, topsoil also needs to be protected from wind, Wllter, lll'ld other agents of erosion. Whllt can be the result of excessive soil erosion? People learned the hard answ('r in the \9305. Up until th('n, mllny farmers in the Great Plllins practiced poor soil mllnagem('nt. As a result, crops sometimes were poor and the topsoil was left bMe. Conditions WOTS('ned during a long drought, which dried the topsoil. . Winds simply picked up the topsoIl ;md carried it away. The region where this happened became known as the Dust Bowl. Huge dust storms swept across the area, and winds carried soil far from the farmlands. Without topsoil, Experts estimate that about 850 million tons of topsoil were lost in the dust storms of 1935. Today, In p
farmers were unable to grow crops for many years. Without crops, a food shorta ge set in. Today, farmers follow much smMter soil conservation plans. One way farmers prel"ent wind erosion of the topsoil is by creilting windbreilks, or shelterbelts. A windbreak is a line of trees planted along the edge of a field. The trees help block the wind and pI'Cvent or reduce soil erosion. Water is another factor in soil erosion. When water movcs down the slopes of a plowed field. it picks up soil and carri cs it away. To reduce this type of erosion, farmers practice contour plowing. They follow the contours of their fields as they plow. These winding furrows 5101\1 water down as gral'il)' movcs it down the slope. Another approach to prel'enting soil erosion is to plant cover crops. such as dover or alfalfa. The roots of these plilnts hold soil in place ;md prevent it from being carried aWily. How do planU

Review

o MAIN IDEA What layers make up a mature soil profile?

Soil is made up of weathertd rl,Kk material, gases. water, and humus. Decaying plants and animals add nutrients to the soil. Topsoil is impouant because it provides most of the nutrients for growing plants.

Conservation practices help farmers prevent the 1055 of topsoil through erosion. "Du
f) VOCABULARY In your own words. define the term soil profile.

€) READING SKill: Draw Concl usions You notice that the steep sides of a highway road cut are covered in tightly wwen netting. What might be the reason for this practice?

o CRfTlCAl THINKING: Analyze Why do farmers need to understand the nutrients required by the oops that they plant?

o INQUIRY SKill: Observe You

dig up pan of your yard in hopes 01 planting a garden. You see that the uppermost layer of soil is thin, and you find a lot 01 rocks near the surface. What does this tell you about how your garden will grow?

prevented.

MATH Estimate Using Fractions A farmer

.,tTEST PREP

practices crop rotation to conserve soil nutrients. She grows wheat one year in every five. About wha t fraction of her total crop output is wheat?

The layer of mature soil that contains only a lew nutrients is ,",

WRITING Narrati ve Find out more about

A. bedrock.

the Oust Bowl of the 1930s. Write a shon story describing what it must have been li~e to be a farmer in the Great Plains du ring the 1930s.

B. parent material. C. subsoil.

O. topsoil. ~ Technology

iii.

Visit w_.eduplacuomlscpl

to lioo out more abool 'iIli1.

How Can People Use Resources Wisely? Why It Matters ... Why should you recycle old

bottles and cans? One reason is to

conserve Earth's resources. Recycling plast ics, me tals, and othe r materials means they can be used to make new

products.

PREPARE TO INVESTIGATE

Inquiry Skill Collaborate When you co llaborate, you work with

other people to find soluti ons by considering the suggestions, f indings, and ideas of others.

Science and Math Toolbox Fur

~tl'p)

2 tu 4, Il'Vil'W M
a Cllart to Organize Data 00 pageHl 1.

Recycling! Procedure

o

Collaborate As a class, identify all the materials that your family, your school. and your community recycle.

o Record Data

In your Science Notebook,

list the materials that the class identified.

o o

Create a chart like the one shown.

Predict Review your list and choose two types of recyclable materials that your household uses. Predict how many of these recyclable items your household uses in a week. Then predict how many of the goods will be recycled. Record your predictions.

......mlnum o.~.

Observe For one week, monitor your household's use of the selected recyclable goods. Record how many items are recycled

and how many are thrown in the trash.

Conclusion 1.

Analyze Data Use your data to calculate the total amount of your chosen recyclable goods used in your household that week. Then, calculate the percentage of those materials that were set aside to be recycled. Did your household recycle more or less than it threw in the trash?

2.

Collaborate Work in a small group to develop a plan that would encourage people in your community to recycte more.

Inve'Stigate More! Solve a Problem

From your data or othef obseNations, choose a resource that you think is wastro in your
v

af1l by

Reading

VOCABULARY

Conservation MAtN IDEA By redudng.

p. (91

READING SKILL Problem and Solution

Use a charI to compare the pros and (ons of one of the conservation solutions discussed in this lesson.

re u~in g.

" nd r eqd ing, people

(all help en~u'e thai import,lIlt reso u«es use d 10 "",ke everyd ay items w ill be ava ilab le in the future.

Using Resources Wisely Thin k about some of the things you used today-a plastic wa ter bottle, a n aluminum '
paper towel. These are very useful items, and all come from nalural resources. Plastic is a petroleumbased product. Aluminum comes from a mineral ore that is mined. Paper is made from trees. When you finished using these items, \Vhilt did you do with them? Did )'ou throw them away in the trash? If so, the resources used 10 ma ke these items are lost. But it doesn't have to be that way. Recycling means re.:overing a resource from one item and using that resource to make another item. Recycling s.wes energy and conserves resources.

Recycling Ra tes in t he United States (2002-2003)

"" ."

.'"'". "

Beve
".

Plasli( Bottle.

Newspapers

Req.clable Item

• How do you thi nk the !,ash that you throw out compares to the data shown here?
Recycle

The triple-arrow symbol means t hat this tan shou ld be recycled. 8 • l esson 3

Gin s ( onta;"",.

The Three Rs of Conservation There are three main ways to conserve resources: reduce, reuse, and recycle. People refer to these as tile Ihree Rs of conserva tion. You h.1I'e already leamed how recycling helps conserve resources. Reducing simply means using less materiil!' For example, when you use one paper towel to wipe up a spill instead of using two, you reduce your use of paper. If you choose not to use a straw in your drink, you reduce the amount of plastic you use. E\'ery time you walk or ride a bike instead of riding in a ca r, you reduce the amount of fossil fuels that you use. Reusing is another way to conserve resources. Reusing can be .15 simple as using a glass cu p again and again instead of throwing away a plastic cup after a single use. Reusing also means putting things to new uses. For example, you could wash an empty plastic pickle jar and keep it on your desk liS a pencil holder. This keeps the jllr from ending up in the gllrbilge. It also saves the material that would have been used to make a pencil holder that you otherwise might have bought at a store. In general, reducing and reusing are more effectin.' than recycling. Both save more resources and energy than recycling does. But recycling resources is still much better than wilsting them. How does recycling to conserve lKl tural resources?

Reuse These containers and clOlh diapers can be used o~r and over again. What other reusable items can you name? ~

... Reduce Insulation llelps reduct Iht amount of energy used in buildings. This fiberglass insulation helps keep a house coolin the summer and warm in the win ter.

landfills Have you ever wondered what happens to the trash that you throw

away? You mily know that a truck picks it up. but where does thc truck lake it?

Mos t trash ends up in a l.mdfilL A landfill is a place where trash is deposited and then covered with plastic or day. The plllSlic or clay

seals the trash in Ihc landfill and keeps the wastes contained. Landfills are carefully designed to keep waste in and water and air out.

This design has both benefits and drawbacks. The sealing of landfills kccps materials in thc waste from polluting thc environment. Harmful chemicals arc stopped from seeping into Ihc groundwater. Yet thc l
quickly when exposed to air and water. However, whCfl scaled in 11

landfill, they might take several years to break down. Other wastes can take hundreds of years to decompose. Trash you throw ou t today may remain in landfills for a \"ery long time. E.1ch landfill is designed to take up a certain amount of space. Once it is filled, it must be closed. Some com munities ha ve no more space to create new landfills. They must shi p their trash to other areas for disposal. When we reduce, reu se, and nxyc1e items that would otherwise be thrown out as trash, we decrease the amount of ma terial thai is sent to landfills. Not only are resources conserved, but space in landfills is also conserved. Why

mu ~ 1

;;;;fun, ..,.',,"

land fill~ take up valuable land resour(e~ Practi(ing the three

Rs reduces th e traSh that goes to the landfilL

0 Silver

•

••

Oil Iron Diamonds

• C,,,..

•

•

C~ ,

Gotd

•

This map sllows wh ere na tural rH OUlteS aft found. When resources are not located near where they aft used. other resources must be used to transport them . ...

Where the Resources Are The map on this page shows

places around the world thnl hllve [MgC deposits of different na tural resources. You can see that many resources are found only in certa in parts of the world. In the past, people often settled in areas where important resQurre5 were found. The natur,,1 rcsoUTCt'S

available in an area shaped the lives and busincss-es of communities in the region. While this is still true to some ex tent, modern transportalion and technology make it much easier for

people to use and rely on rcsourres from all over the world. Today, people commonly transport resourccs. A rcsource such '"'s sih'cr may be taken from the place it is mined and shipped to another place to" - p~-- .... p"~ ~i l v,' ,-. th O" vt: ' ......... "'''"''''' " ' " '" " shipped all ove r the world to jewelers and other manufacturers.

Oil is one resource that is used everyv.·hcre, but found in large ~upplies in only II few plllccs. every d ay, s hi ps carry millions of gall ons of oil across the oceans. These ships sometimes have acciden ts, and their cargoes spill into the wa ter. Oil s pills can be deadly to fish, whales, seals, and other marine life. Evcntually, the oil can wash up on land and damage ecosystems along thc shore. Transporting resources arou nd the world brings many bencfits. Howc\,{'r, it can also be cos tly and hann the environmen t. When people conserve n'ltural resources through th{' Ihl"C(> Rs of conservation, fewer resources need to be shipped around the world. 'ROIUW AND SOLUTION

Wh",

is one sol ution to Ih'" problems caused by

transporting oil?

-------..:--:..----------~~b

Review

o MAIN IDEA What are thre{> Resources can be conserved and pollution reduced by reducing. reu~ing. and re
Landfills are specially designed places to dispose of wastes.

pra
(} VOCABULARY Write a short paragraph that explains how recycling conserves natural resources.

o READING SKILL: Prob lem

an d Soluti on landfi lls are lined with plastic or clay. What problem does this help to solve?

o CRITICAL THINKING: App ly Natural reSOurUS are transported regularly from regions where they are found to other regions where they are

"'"' for Home and School

MATH Make a Graph Use newspapers, almanacs, and the Internet to find out the average amount of trash produced by a nearby city each year for the last five years. Ma~e a line graph showing the data. Analyze the trends you find .

TECHNOLOGY Write a Report Research developments in the design and location of landfills. Write a report explaining what you learned.

Cobalt is a metal used in making powerful magnets. The United States imports all its cobalt from other countries. If large cobalt deposits were found in the Rocky Mount~ins. how might thl'lt ~ffecl the United States and other coontries ?

o INQUIRY SKILL: Collaborate

Wor.: with a partnet to list thre{> ways of reducing the use of natural resources at your school.

~TEST PREP Which of the following is NOT a method of conserving resources? A. replace B. re
~ Technology

'Ill Vi!.it www.eduplace.comlscpl \0

find out mole about how Iesources

can be used wisely.

8 • l esson 3

Cartographer Cartographers are map makers. They map many types of surface features, from the highest mountain to t he o<ean floor. Maps may present natural features, such as elevation and climate, or human-made ones, such as cities,

roads, and (fOps. Cartographers rely on physical surveys, as well as images from airplanes and satellites.

They often use computers, too. What It Takes!

• A degree in geography, geology, or art • Drawing and comput er skills

Farmer Is farming the most important job in the world? Nearly all of the wor ld's food comes from crops and livesta<:k raised by farmers and ranchers. So do many other products, such as cotton, leather, and wool. Farmers must do many tasks: ope rate and care for f arm machinery, monitor weather conditions, prevent (fOP and animal diseases, care for the soil, and manage a business.

Wkat It Takes! • Courses in agriculture and business • Energy f or st renuous work outdoors

What a waste!

It took millions

of gallons of fossil fuel and many other nonre newable resources to make the tires in this picture. Every year hundreds of millions of tires are thrown away. Experts estimate there are at least 1 billion scrap tires in the United States! Because tires take up to 80 years to decompose, they aren't going away so on. Fortunately, recycling tires has become big business. Each year, more and more old tires are processed to produce fuel. Tires are also ground up and used to create safe, sturdy surfaces for roads, sidewalks, and playgrounds.

READING

: Compare and Contrast

Run a rope through the billion tires in

U.S. landfills today.

You'll have a tire necklace long enough to circle the earth 5 times!

Tire Doctor Dr. Jagdlsh Dhawan, shown her., worked with ,.lIow chemistry prof.ssor Richard L-tendN to develop • nIIW procesl that

r.cycle, scrap tlr.s Into high-grade oil without

any.ast• .

Vocabulary Comple te each sente nce wi th a term from the list. 1. Sending aiuminl,llll cans to a plant to be made into other

aiuminl,llll proWcts is an eKampie of _

(onstnIation (SO

fossil fuel (71

2. A(n) __ is anything found in nature that is nectssary Of useful to humans. bKaust it fOfmtd

3. Coal is called a(n) _

"om

ancitnt living things.

natllral resource (76 nonrenewable resollrce (17 the remains of rt
4. The I.lytrs that make up a mature soil rtpftsent the _

S. Humus is most commonly found in _

6. The layK of soil with little Of no OIgank matter is called _ 7. __ is soil that is located where it fOfmed.

8. A(n) __ may only be used once because it cannot be replaced.

soil (86 soil profile (88 subsoil (88 topsoil (88 transported soil (81

!t. ~lllhal has been camed by Wind or water worn where II

formed is called _

.

10. A(n) __ may be used repeatedly, because it can be replaced.

I Test Prep Write th e letter of th e best answer choice. 11 . The practice 01 using all rtsOllfcts wisely is 13. What is one example of capturing a l efl@Wabk> roergy source? called _ A. (OIlSl'fYaOOn B. IIIoing ",,,, ..·al* ~I'S C. IIIoing non,erllhvabit rtsOUrcl'S O. comp:ostlng

12. Which is NOT a common part 01 soil? A. humus

B.

watl'f

(100· (hapter 8

A. mining for coat B. mining for oil C. inslalling wind lUibines D. drinking II glass of Willer

14. Using china dishes instead of paper platts is an example of __ "''''' ~ A. reducing B. rl'llSing

C. recycling D. UnwM

Inquiry Skills 15. Observe How could you use the

appearallCe of a creek after a rainstoJlll to determine if soil erosion is taking place? 16. Collaborate How might people work

together to reduce the amount of trash that is sent to a landfill? Discuss positive steps that families. businesses. and communities can take.

17. Evaluate How would you respond to people who say it is not ne<essary to COnseNe fossil fuels. because the supply of fossil fuels will not run out during their lifetime? 18. Apply Name three different types of resources that people mine from Earth. Describe uses for these resources. 19. Apply If you were inteNiewing a company to pick up your materials for recycling. what are three questions you woul d ask? 20. Analyze What natural resources are

espe
Performance Assessment

Map the Concept This chart shows two categories. Classify each of these Il(Itural resouf{es. (oal oil trees solar energy natural gas wind energy moving water

Renewable Resource

Plowing a Field Suppose a farmer wanted to che
Write tile letter of til e beu answer choice. 1. Rox. ~eeps her pens and pencils in an old tennis ban tan. Whicll conservation strategy is this? A. B. C. D.

recycle reduce

resource reuse

4. Soil tllat forms from tile bedrock below it

is calledl _ __ A. humus. B. rocky soil. C. residual so~. D. transported soil. 5. Which is a nonrenewable energy SOlUte?

2. Which surface feature do living organisms

build up?

A• _ _' "

A. c«al reef

B. river delta C. shield

(()rle

D. terminal moraille

3. The diagram shows which type of pla te boundary?

A. converging

B. divefging C. sliding D. subducting

6. W1licll of the following provide fYidence to support the theory of continental drift? A. atolls

B. caves C. deltas D. fossils

( " 02 • Unit ( )

7. 'MJkh of the following is NOT a featur@ of tile dHp oc@anfloor? A. guyot B. seamount C. abyssal plain D. continflllal margin 8. Which repfesents a destructiv@ force on Earth·s surlace1

• B.

c.

Answer th@following in complete sentences. , . Hybrid cars run on gasoline some of the time and on ele
On January 17, 1994, a strong earthquake struck southern California. The epicenter was near the community of Northridge, and the magnitude was 6.7 on the Richter scale. The map shows how strongly the shakin9 was felt in different communities. Richter Scale

,

, , , • , .

. --- - -,,- ---- --...... ---...... --.--2

•

3

~. -

~"'

_Ott

.,

~

"9' _

,,~

~

.,

,,~

S~ . k l · 1

--,.

,~ ,

PACIFIC OCEAN

,

•

..-

Earthquakes strike when lOCh suddenly break deep below Earth's surface. In a ~evere earthquake, the ~hock waves can topple buildin~ and collapse bridges. Earthqua~es are common along the edge 01 the Pacific OCean. w~e tectonic pjates are slowly slidirl9 again$! one al">Other. See an earthquake in action. Go to www.eduplace.comlscpl toviewa flash'M movie alld to learn IllOff about earthqua kes.

---

Atmosphere and Solar System Chapter 9 Weather and Climate .........................................D2 Chapter 10 Earth and Its Moon .......................................... D28 Chapter 11

Exploring Space ............................................... 052

Independent Reading

Torn.ado

Chasl!~

Space Wardrobe

15 Faro About Stars

You look up at the night sky an d see countl ess numbers of twinkl ing stars. Some stars appear large r and brighter than others. And so me seem more twinkly than their neighbors. What makes stars appea r to twinkle? You'll have th e answer to this question by the end of the unit.

LESSON

1 LESSON

2

Winter-or summer-

wonderland? Why is the Arctic always cold?

Read about it in lesson 1.

How does hi-tech equipment in space help you decide what clothes you snould wear? Read about it in lesson 2.

Factors Affect Climate? Why It Matters ... All organisms, including humans, are affected by the dimate of the part of the world they live in. Understanding the factors that affect climate helps people predict and

prepare for changes in weather.

PREPARE TO INVESTIGATE

Inquiry Skill Compare When you compare, yo u describe how two or more

objects or events are the same and how they are different.

Materials • graph paper, 2 sheets • m~t~r Slick

• protractor • large lIashlight

Science and Math Toolbox foI step S. [e'oIiew Measurements OIl page H16.

Lighten Up! Procedure Safety: Do not shine the light into anyone's eyes, including you r own.

o e e

e e

Collaborate Work with a partner. Place a sheet of graph paper on the floor in your work area. Measure Hold the flashlight 112 meter above the graph paper and pointed direaly at it, When the room has been darkened, shine

the flashlight directly onto the center of the graph paper at an angle of 90 degrees. Record Data While you hold the light steady, have you r partner careful ly trace the lighted area of the graph paper. Label the drawing, Pick up the graph paper and replace it with a clean piece. Now tilt the flashlight at an angle of 45 degrees to the graph paper. Use a

protractor to help you determine the angle. Repeat steps 2 and 3. Use Numbers Count the squares inside each shape traced in the sheets of graph paper to find the areas of the two shapes. Record the areas in your Science Notebook.

Conclusion 1.

Compare What differences did you notice between the two lighted areas? How do the two areas compare?

2.

How might the difference in the lighted areas explain why Earth's surface is not evenly heated by the Sun?

Investigate More! Design an Experiment Design an experiment to show how striking a WIVed surface, such as a large ball, affects the angle of

the Sun's rays. Predict what will happen. then test your prediction.

\.eat~ by Reading VOCABULARY climate

p. 07

ocean (u rrents

p,OlO

f t Nino

P. 010

READING SKi ll c.. UH ilnd Effect Copy and complete the table 10

MAIN IDEA Clima le is the no.mal pattern of Wfliither in lin are
Uneven Heating • •

show IhI> fil(\~ th.at affKt •

climate.

••

Uneven hea ting of Earth's surface affects the climate

of an area.

In summer, would you Wl'ilr II h.llhing suit at the North Pole? Would you wear a down ;a.ckct in Egypt? No, you would not. l1le North Pole would be 100 cold and EgypllOO hot. Why? E.1rth's shape and the till of its axis cause the Sun's rays to strike different parts of Enrth's surface at different ang les. So, energy from the Sun heats the surface unevenly. Egypt is loca ted near the equa tor, where the Sun's rays strike the su rface at an angle near 90 degrees. This causes these arE'as to be warm rear round. Near the poles, the rays strike the surface at angles much less than 90 degrees, resul ting in much cooler temperatures. What kinds of tempcrntures might you expec t to find in areas between these two regions?

Major Climate Zones

o

e

Tropical climates are very warm and often very rainy.

Temperate climates have warm summers and (001 to very (old winters.

Opolar climates have (old temperatures year round, even during Summer months.

Climate is the normal pattern of weather in an Mea over many years. Uneven heating of Earth's surface by the Sun creates three major climate zones: tropical, temperate, and poi M. The major difference among the clima te zones is their yearly average tem perature and amount of precipi tation. Precipi tation, as you might already know, is any type of wa ter- rain, snow, sleet, or hail- tha t falls from clouds. Tropical climates occur at the equa tor and in Meas just north and south of it. The temperatures in these climates Me very warm year round . The coldest mon th in this type of climate is often no cooler than 15°C (59°F). Tropical climates can receive up to 250 cm (100 in.) of rain per year. However. some tropical areas receive very little rai n. Temperate climate zones lie to the north and south of the tropics. Some tempera te clima tes have mild w in ters and mild summers. Others hilve very warm su mmers and \'ery cold winters. [n temperille cli miltes, much of the precipita tio n in summer is rai n. In winter, it is snow. plilces close to Earth's North Pole and South Pole have polar climates. Tempera tures in these areils Me very cold year ro und. Most of the precipitation falls ilS snow. Study the figure on pilge D6. In w hich clima te zone do you live?

~ CAUSE AMD Efun

How does uneven hea ting by the Sun affect climate on Earth?

.7

Land and Sea Breezes

Sea Breeze A sea breeze flows from the water toward the land. ...

If you've ever been to the short', you mily have noticed thai land ilnd wilter heal up ilnd cool down at different rates. The unequal heating of the two different su rface types cauS('S IOCill winds known as land breezes and sea breezes. Ouring the dilY, land heats faster than Willer. As warm air riS('S O\'er the land, cool ai r mO\'e5 in from th(' wat('r 10 take its place. This creates a sea breeze. At nigh t, ilir moves in the opposite way. Land cools fast('T than water, so lhe air over Ihe willer is warm('r. Wann air rises over Inc wal('r, and rool air moves from land 10 waler. This creates a land bree7.e.

Land Breeze A land breeze flows from lhe land toward Ihe waler. ...

'ht mountains force the w~rm, moist air to liu into coole. p~rts of tht atmosph ere. cilusirlQ t~ water vapor to condense.

Sun p
'Of

T~

Mountain Effect Why are some places rainier than others? Mountains ncar oceans hold part of the answer. These mountains affect the water cycle-the movement of water betv.'een Earth's atmosphere and land. Recall that most of Earth's water is in oceans. When water evaporates from oceans, it becomes water vapor in the air. The warm, moist air rises and moves o\'er land. Air that meets mounl3ins is forced higher, where temperatures are colder. Cold air can hold less water vapor than warm ai r. So, the water condenses into tiny water droplets.

The droplets form douds th.1.t can drop rain or snow along one side of the mountain. This side, which faces the wind, is called the windward side of a moun tain. Some of the wettest places on Earth are on the windward sides of mountains. When the air finally crosses to the o ther side of the mountain, it usu ally has very little moisture left. Dry w inds sweep down this side of the mountain, which is called the leeward side. These dry areas on the leeward slopes arc called rain shadows. Desert climates arc common in rain shadows.

i";'

U.USEAND EfflU

Deu, ibe the

diffe,enc:e in pr~ipilation on the leeward side ar>d windward side of a mountain.

Mountain Effect Pretipitation

8,

'

pasm over tM mountains. almost all tM moisture has

fallen OUI of it.

Ocean Surface Currents

•

•

• Ocean currents move water and energy from place to place.

Oceans and Climate As the m.1p alxwe shows. about 70 percent of Ea rth's surface is oovcN'd by wa ter. Most of this is ocean wa ter. Ocean waters absorb huge amounts of energy from the Sun. Recall that regions near the equator absorb more energy than those near thc poles. So, ocean waters art' warmest nea r the equa tor and coldest near the poles. Air just above warm ocean water is warmed by the wa ter below. The warm air rises and cooler ai r moves i ~ to take its place. This exchange of mr near Earth 's surface crt'a tes winds. Winds blowing across the ocean create mo\'ing streams of water called ocean currents.

OHI . Chapler 9 · Lesson

The curren ts shown on the map above are su rface cur rents. As you Cilll :.0,.""', ~IIIC cur"""b il"" ",,,rill and o thers are cold. Warm cu rrents movc warm ocean water toward polar "-'8ions. Cold CUl'n"nts move cold ocean wa ter toward the equa to r. These (Ul'n"nts have a moderating effect on world climates. Li ke many pattcrns in na ture, the p.1ltem of ocean currents can change from time to time. EI Ni no is a name gi\'cn to a periodic change in direction of Wilrm ocean currents across the Pacific Ocean. £1 Nino events occur every fi\'e to seven years, and can cause tempora ry changes in clima te around the globe. (tUU ANO (fF((T

How do ocean currents aHect clima te?

Review

o MAIN IDEA What are some factors that affect climate?

Uneven he~tin9 by the Sun (au leI lome partl of Earth to be warmer than othe.l.

o VOCABULARY 'Nhat are ocean currents? What sets them in motion?

9 Climate is the normal pattern 01 ~ather in an area over many years.

80diel of wate., mountain\, and ocean currenu can affect climate.

READING 5KllL: Cause and Effect Offi:ribe two ways in which bodit$ of water can affect climate. Use these words in your answer: land breeze sea breeze and ocean currents.

G CRITICAL THINKING: 5ynthesize Study the illustrations on pages D6 alld 010. What kim:! of climate do you think Miami. Florida. has? Explain.

4) INQUIRY SKILL: Cause and Effect What faders help to account for the differences among tropical. temperate. and polar climates?

MATH Find an Averag e This table shows the amount of precipitation in Portland, Oregon, during a five·year period. Find the average yearly rainfall during this period. Year 1

Predpitat ion (em) Year 2 Year 3 Year 4 Year 5

83.3

8S.!

74.9

71.0

88.7

WRITING Expository Research EI Nino. Wha t do scientists think is its cause? How does it affect fishing, ocean transportation. or other human activities? Write a short essay to present your findings.

.,tTEST PREP Ocean currents affect climate because they A. are always cold. B. are always warm. C move water and energy from

one place to another. O. cause winds to move air from one place to another. ~ Technology

, . Vilil w_.edupla(uomls(pIIOlind oot more ~I>oot di""'te. Dl1

Biography Luke Howard (1772-1864) •

• •

Luke Howard ('nmed his living;ls n busincssmlln. He ran 11 com pan y in England that made and sold medicines. Yel today he is remembered for his favorite hobby, which was studying clouds. Among Howard's influences was Carolus Linnlleus, the scien tist who developed the dassifkalion s<:herne for living things. Howard

deddcd that clouds could be clnssified as well. In a speech he delivered in 1802, Howard described four classes of clouds. The classes are listed in the table. Howard chose L.1tin names because L.1lin was

known to all scientists of Ihe time. Howard preSi'ntl>d his essay nnt at n UniVf'Tsit}'

or other formal institution, but 10 a discussion group that met at a priv,,!c home. Nevertheless, his ess.1y was published, and his names for clouds became very popular.

Cumulus (Heap)

Stratus (Layer)

Nimbus (Rain)

Cirrus (Curl)

Heaps Illal pile over a Ilat base

Widely e ~le ndt{l II orizonlal slleel

Cloud syslem llIal produ(es rain

Fibers Illal spread in any and aU dire(liom

012· Chapler 9 · Lesson 1

SOCIAL STUDIES

June Bacon-Bercey (1934-)

." . ,

As a young woman, June Bacon -Bercey was not sure if she would

live out her dream of be<:oming a me teorologist. "I was discouraged, and other women were, too," sht> said. One of the problems was

paying for the education she needed. Yet 13.1con-Bercey p<:>rscvcred, raising funds however she could. And over

time, she was rewarded for her efforts. For many years, she worked as a

professional meteorologist and reporter for a television station in Bufflllo, New York. In 1979, she was hired as Chief Administrator of television activi ties for the National Ocea nic and Atmospheric Agency (NOAA). As her career progressed, she became recognized as an international expert on the weather. Yet success for herself WilS not

8acon-8ercey and other scientists at NOAA work enough. In 1977, Bacon-Bereey won thousands of dollars on a television q uiz to forecast the weather, study oceans and show. She used the money to establish coastlines, and proted a schol~rship for women who want to the environment. become meteorologists. "If ]women] feel they've got some money behind them, it might be better," she Solid.

1. READING (HECK How did Luke Howard class ify douds? 2. WRITE ABOUT IT Compare the stories of Luke Howard and June 8acon·8erce')'.

3. TALK ABOUT IT In what ways ale Howard and Bacon-Bercey good role models to follow?

How Are Weather Forecasts e? Why It Matters ... Who

d~pends

on the weather

forecast? Farmers need to know the weather before plowing fields or harvesting trOps. Airplane pilots need to plan the ben roules.. And many businesses, Irom outdoor restaurants to baseball teams. make plans based on the weather.

Sometimes everyone depends on the forecast. When a sellere storm approaches. the correct forecast can salle people's lives.

PREPARE TO INVESTlGATE

Inquiry Skill Collaborate When you collaborate, you work with others to (onduct ellperiments. eJtchange informalion, and

draw conclusions..

Materials • 2 loolill unilln"leo.i I.>dIlWlI~

• scissors • small baby food jar • 2 thick ,ubbtr ball
The Pressure's On! Procedure Safety: Be careful when using scissors.

o o

o

Collaborate Work with a partner. Cut the top off of two balloons. Then, cut one of the balloons 113 of the way down. Stretch the smaller balloon over the mouth of the smaller jar until it is tight. Secure it with a rubber bclnd. Tape a toothpick on the balloon over the center of the mouth of the jar. leaving the toothpick hanging over the lip of the jar. Carefully place the small jar inside the larger jar. Stretch the larger balloon tightly over the mouth of the large jar. Secure It

with a rubber band.

G

Experiment While one partner holds the large jar, the other partner should push down on the balloon to increase the air

pressure inside the large jar. "

Observe In your Science Notebook, record

what happens to the toothpick when the balloon is stretched downward.

"

Experiment Repeat step 4. this time pulling up on the balloon. Record what happens to the toothpick.

Conclusion 1. l

-

2.

Infer How does pulling up on the balloon

Design an Experiment How coold yoo modify this experiment to deteCI actual

affect the air pressure inside the jar?

ma~ina~k

Hypothesize What does your model show

ilir pressure? Compaf~ your observiltions with air pressures ~sted in the

about how changes in air pressure can be observed?

<

Investigate More! -

-.

v afn by Reading VOCABULARY

Earth's Main Idea Earth 's "tmosphe,e is a mixture of gases

air mass

p. D18

atmosphere

p,016

front

p, 019

mesosphere stratosphere thermosphere

p,OH p. 0\7

troposphere

p.0\7

p.OI7

th"l surrounds the planet. Changes in this bl'lnkel of air cause changes in weather. Weather Can be foreCilst using different tools.

Composition of Earth's Atmosphere Earth's atmosphere is a mixture of gases that surrounds the planet. This ocean of air is made

mostly of nitrogen and oxygen. Other gases are

READING SKILL

Draw Conclusions Se lect

one of the air masses des
DO

present in very small amounts. As you can see

from the grilph below, argon makes up about 0.93 percent of dry air. Carbon dioxide makes up about 0.03 percent of dry air. Neon and helium each make up a tiny percentage of our atmosphere. The amount of anyone gas in the atmosphere can vary. [n dry air, for exam ple, there is li ttle or no water vapor. In the moist air o\'er an ocean, water vapor can make up four percent of the air. Carbon dioxide is another gas that is present in the atmosphere in varying amounts. You might already knoll' that the amount of this gas in the atmosphere increases when fossil fuels are burned.

Composition of Air

Nitrogen

"" Air is mostly nitrogen and oxygen. Other gases are present in small amounts. Lesson 2

Structure of the Atmosphere Earth's atmosphere can be divided into four main layers. The layer closest to Earth, where almost ~1l weather occurs, is the troposphere. Although it is the thinnest layer, the troposphere contains about 75 percent of the gases that make up the atmosphere. Temper~ture and air pressure decrease with distance from Earth's surface. Air pressure, which is an importan t element of weather, is caused by the weight of the gases in the atmosphere. Air pressure affec ts the wa ter cycle which, in turn, affects the we~ther. The stratosphere lies above the troposphere. Air in thi s layer is much colder and drier than air in the troposphere. The stratosphere contains most of our planet's ozone, a form of oxygen. Ozone absorbs certain types of radiation from the Sun that can harm living things. The mesos phere lies "OO\'e the str"losphere. The top of the mesosphere is the coldest part of Earth's atmosphere. The very thin air of the thermosphere is the first part of the atmosphere struc k by sunlight. Temperatures in the thermosphere can reach 1,700°C.

D DRAW (ON(lUSIONS

Why does moU weather OCCur in

t he troposphere?

f'lrth'~ atmo~phere

is a form four main layers.

mi~ture

of gases that

--

Troposphere ~

Air Mass Formation

cP

... Different air masses bring air of different temperatures and water content to North America.

K"

,

..... polar tropical cont inental tropica l

Air Masses In the troposph('re, wh('re almost a][ weath('r occurs, large volumes of air cillled ai r masses are always mov ing. An air mass is a body of air that has about the S<1me temperature and moisture throughout. The temperature and moisture properties of an air mass depend on where it de\·('lops. Polar ai r masses form at middle to high latitudes ilnd are generally cold. Tropical air masses form at low lati tudes and tend to be warm. Continental air masses form over land and are generally dry. Mari time ilir masses form over water and are moist. The map above shows the types of air masses that affect most of North America . Not ice that pai rs of letters are used to id('T1tify the differen t air masses. Taken together, each pai r identi fies the moisture and temperature properties of the air mass. 018 • Chapter 9 • l esson 2 )

Lower-case lett('rs m and c are used to represent maritime (moist) and COlililll'll/al (dry). Upper-case, or capital, lett('rs P and T arc used for po/ar (cold ) and tropical (warm). Find the mP and mT air masses on th e map. These moist air masses are responsible for fog and drizzle in coastal regions. They also bring moisture to the center of the country. Now loca te and cP and cT air masses. These air masses, which form over land. con tain little mois tu re. When such air masses move into an area, th ey generally bring fair weather. Noll' look at the map to fi nd the type of air !TI.1SS responsible for much of the weat her in your area. What are its properties? Is it humid or d ry? Warm or cold? Does this agree with the type of weather your area experiences?

Fronts When two air masses meet, a front forms. A weather front is the boundary between two air masses with different properties. The approach of a front is usually marked by a change in the weather. Such changes occur be<:aus.c cold air is denser than warm air. A warm fron t forms when a warm air mass moves into an area of colder ai r. The warm air slides up and over the colder air, forming a gently sloping front. A warm front generally brings a large area of douds and precipitation. On a weather map, a warm front is shown by a red line with red half circles along one side. A cold front forms when cold air pushes its way into a warmer air mass. The dense cold air forces warmer air to rapidly rise high into the atmosphere. Clouds, heavy rain, and thunderstorms are produced along cold fronts. On a weather map, a cold front is shown by a blue line with blue triangles. Sometimes when two air masses meet, neither mass moves forward. This type of front is called a stationary front. On a weather map, a stationary front is shown by a line with both red half circles and blue triangles.

Warm Front

-

,

A warm front forms when warm air moves into an area. light rains are assodated with warm fron!$.

Cold Front

A mid front forms when (old air mOveS into an area. Heavy raiM often form along a (old fronl.

~ DIlAW (OHUUSIOHS

How do air masses a ffect weather1

D19

Observing Weather Weather is th e overall condition of the iltmosphere at a given time and place. Meteorologists are scientists who study wea ther. They make observations and collect datil. Every few hours they record thei r findings on il weather map like the one below. By stud ying a series of maps, meteorologists are able to forecast future wea ther conditions. Like all maps, wea ther maps use symbols. A key is provided to help understand the map. Study the map and look for the symbols for fronts as described on page 019. Identify and locate the wann fronts and cold fronts. Symbols are also used to indicate certilin conditions, such as cloud cove r, type of precipitation, and the QCCurn>f1ce of thunderslonns.

Notice thai colors are used to represen t air temperatures. In the United States, temperatu re is usuall y reported in degrees Fah renheit. Weather maps illso identify areas of high ilnd low air pressure. In a high-pressure system, indiciltcd by an H• air sinks to the surface and moves away from the center. High-pressure systems usua lly have cleilr wea ther. In a low-pressure system, shown by an L, ai r at the center of the system rises. Air around the sySlem moves in lowards the center to take the place of the rising air. Cloudy and rainy weather is usually present in a low-pressure system. Most weilther systems move from west to east across the Uni ted Slates. Look ill the map below. What kind of weilther might you expect in Texils in a few days?

Data from many sources are combined on maps that can be used to forecast lhe

weat~h~H~'i':"~I~:~:~;;;~~~~;;;:~~~\

fI

T-S1OmII

d

Rain

*o ....

Sunny

D _

• Chapter 9 • tesson 2

Radar 0 3:32 ....M. HUffi(ane Charley first struck Florida in th early morning_

o

11:53 ....1Il.

HUffi(ane Charley continued to

move up the wl'''I',n " " 0< 1.

€) 1:S1 '.M. Heavy rain. fell over much of Florida as the storm moved acrOSS the state.

Hurricane Charley 2004

A useful tool for observing and forecasting weather is rad ar. A wealher radar transmitter sends out radio signals. When these signals hit rain, snow, or other forms of precipitation, the signals bounce back to the transm itter and are record ed . These radar signals can be used to create an image of a s torm. You may have seen radar images, which look like fu zzy patches. used in weather reports on television. Study the three images to the left. They are some of the early radar images of Hurricane Charley, which struck Florida in 2004. Note the diffe ren t colors in the images. The colors indicate the strength of the rain brought by the hurricane. Where is the rainfall light? Where in the storm system is the rainfall the heaviest? Radar can also be used to determine how large a s torm is, how fast it is moving, and where it is headed. With this information, forecasters can warn people when severe storms are approaching. In the case of IMge, destructive storms, such as hurricanes, early warnings can save lives and property. Look again at the radar images on this page. In what direction did Charley move as it passed over Florid a?

~ DRAW (ONCLIISIONS

What are two types of weather data that (an be observed with radar1

'21

Other Weather Instruments Weather satellites are anot her important tool used in observing and forecasti ng weather. S.,tellites orbit high above EMth and use ins truments to gather data from the upper atmosphere. Information from these instru ments can be used to determine temperatures and wind sp«
Weather vanes are used to indicate the dir«tion Irom wIlich wind is blowing. ...

'NIIy lire weilther sa tellit es lin importa nt toot for wea the r lore-cas ters?

Thermometers

Anemometers

Barometers

I re used to measure temperature. They may report degrees fahrenheit ,"F). degrees CelSius ("C). Of bo th. ...

musure wind speed. SOme also Indicate the dlr« tion 01 the wind . ...

me.sure iir pressure. In the United Stitn. air prHsure i1 usually repor ted in inches of mercury. ...

022 • Chapter g • l esson 2

Rain gauges lire used to coiled lII>d meHUre tile amount of rain, snow, sleet. Or hail. II the precipitation illOlid. it is melted belore it is musu,ed . ...

Review

o MAIN IDEA What are the four main layers of Earth's atmosphere?

The atmosphere is a blanket of air that sUffounds Earth.

a VOCABULARY What is an air mass and what determines its properties?

f) READING SKill..: Draw Conclusions Suppose your area is eXpe!"ieflCing thunderstorms. What kinds of changes in the atmosphere led to the formation of the storms?

large bodies of air. called air masses. form in tile layer 01 the atmosphere closest to Ea rth. These air masses meet to form fronts. along which ~ather cllanges occur.

o CRITICAL THINKING: Apply How might radar images help to reduce damage hom an approaching storm?

Oifje,ent kinds 01 instruments can be used to make observations about the weather.

o INQUIRY SKILL: Collaborate

.e MakeaTable Research an extreme weather event that has occurred in your area. Make a table to compare temperatures, wind speeds. and p.edpitation during the storm with the normal values fOr that time of year. Beaforecaster Use the Internet to prepare today's weather fo recast. Include sa tellite images that show the weather in your area, and .elate them to the forecast. Present your forecast to the class.

TEST PREP Weather fronts form when A. air masm meet.

MATH

TECHNOLOGY

How might sharing data gathered in different regions allow scientists to better prediCl the weather?

B. air masses form .

C. cold air rises. D. warm air sinh.

t-t '.

Technology Visi1 w_.edupla<e.
It can rumble like an avalanche. It can roar IIka a freight train. It can scream like a jet engine. Few things can withstand its fury. It's the mightiest wind on earththe tornadol Tornadoes are concentrated, twisting columns of air. They hang from the bottom of spedal, rotating thunderstorms called supereells. Tornadoes contain the fastest winds on earth. The most powerful reach over 300 miles per hourl In April of 1974, the United States had the biggest tornado outbreak In its history. A total of 148 tornadoes hit 13 states. Called the Super Outbreak. this storm system produced 30 devastating F4 and six Incredible FS tornadoes.

READING

: Compare and Contrast

Wedge The most powerful lorlladoes often have a wedge shape. The largest wedges an span a mile or two aCfOSS-

Rope

Many tornadoes end their lives in what is called the rope stage. Although thin and strung out, the winds of a roped-out

lo ...... do (an still do great damage.

Fujita Scale

Vocabulary Complete each sentence with a term from the list. Some terms may be used more than once.

I . __ is the range of no«nal weathe.- conditions in an area Oye.- along pefiod of tim!. 1. A large body 01 air that has similar pfOperties 01 t!mperature and moisture is a(n) _ . 3. A(n) _

fOfms when two air ma$WS with diffefent properties meet.

4. MOIIements of large volumes of ocean wate.- 31! called _ 5. Earth'$ __ is a mixture of ~ that Sllnounds the planet

6. The layer of Earth·s atmosphere where most weather takes place is the

air maSI 018 atmosphere 016

climate D6 EI Nii\o 010 front 019 mesosphe re 017 ocean currents 010

stratosphere 017 thermosphere 017 troposphere 017

7. The coklest layer of the atrnospllere is the _ 8. lh! hottest laye.- 01 the atmO$phefe i$ the _ 9. A laye.- 01 ozone in the _ _ prote
radiation.

10. During an event called _

warm ocean currents change direction in

the Pacific Ikean.

, Test Prep Write the letter of the best answer choice. 11 . Near the poles. energy from the Sun _ A. doesn'l striu Earth B. slrim Earth at a wrp angle C. strim ElM dirKtIy O. is vtry conctntrated 12. A land breeze is II local wind that blows

n. __ are the two most abundant gases in Earth's atrnospllere.

A. o~ olod helium S, O~ and hydrogen C. Nitrogen and oxygen D. Nitrogen and carbon dioxide 14. A(n) __ forms when warm air mOIIes into

A. only OYer ~nd B. only OYer waler C. from Land towllld wall'( D. from wall'( IOWaId Land

026 • Chapter 9 '"\

an area of cooler air. A. warm fronl B. cold front

C. polar air ma5S O. maritilfle" ma5S

Inquiry Skills 15. Compare Use maps and information from this mapte.- to compare the climate of Florida with the climate of Ohio. What effect do bodies of water have on the climates of these \wo states?

16. Predict Suppose you liV«! in Tampa. Florida. and were planning a picnic. The morning weather report includes the radar image below. OeI;ide whethe.- or not the wea ther will affl?Ct your plans.

17. Inferring look at the photo on page 04. What kind of climate does this area have? Describe the average temperature and amount of precipitation.

18. Applying Where would you expect to find hot dry climates in the United States? Explain your answer. 19. Drawing Condusions The amounts of a specific gas in the atmosphere can change from time 10 time. W'rti do you think this is so? 20. Evaluating Would you expe
Performance Assessment Study today's weather map from the newspaper or the Inte.-ne\. Predict tomorrow's weathe.for a specific area on the map. Compare vour prediction to the actual weatha that place experiences.

Map the Concept The chart shows three pairs of teons. Complete the mart to compare and contrast the terms. lropital dimate

Polar dimate

".d' e

bf ....

",

br .......

Warm front

Cold Iront

LESSON

1

Day or night?This

picture was taken near midnight. Why

is the Sun shining?

Read about it in lesson 1.

LUSON

2

The Moon is Earth's

only natural satellite. Why does it appear to change shape? Read about it in lesson 2.

What Causes Earth's Seasons? Why It Matters ... Winter, sprin g, summer, fall-th.

•

•• PREPARE TO INVESTIGATE ••

seasons repeat year aher year. Yet

Use Models You ca n change a model, observe the resLllts, and then sLlggest how the real

seasons are very di fferent in different

places. hI October, when it is fall in the United States, it is springti me in Australia. Understanding how Earth moves through space is the key to

understanding seasons.

Inquiry Skill

t hing would work if the change • was made. • • •

• Materials • • • : • ••

• • • •

fine-towel! bl~lk "'(I, ke' small plastic foam ball pencil large ye llow ball or

inflated round balloon

Science and Math Toolbox For step 3, review Measurements on page H16.

Reasons for Seasons Procedure

o

Use Models Draw a line Clround the middle of the foam ball, as shown in the diagram. The foam ball represents Earth, and the

line represents the equator.

G

Use Models Carefully push a pencil

completely through the foam ball at a right angle to the equator. The pencil

o

represents Earth's imaginary Clxis.

Collaborate The yellow ball or balloon represents the Sun, Working with a partner, hold the Sun and Earth about

1 meter (3 feet) apart. Hold Earth so the North Pole tilts slightly toward the Sun.

G

Use Variables Move Earth in a circle

around the Sun, making sure that the North Pole always points in the same direction,

"

Communicate Repeat step 4, this time stopping at each quarter trip around the Sun. At each position, discuss how the Sun's rays hit Earth. Have your partner record the positions and observations.

Conclusion 1.

Compare When did Earth's northern half receive the most sunlight? When did the southern half receive the most sunlight?

2.

Analyze Data How does Earth's tilt affect the seasons where you live?

Design an Experiment What if Ear1h·s a~is were not tilted? Or what if its tilt increased? Use models to predid how E
v

af1l by

Reading

Earth's Seasons

VOCABULARY

MAIN IDEA Earth 's .aliltion and its revolution cause d"y

al.llumn,,1 equinox p. 034 p. 032 ilKis revolution p. D33

and nighl
summer solstice

p.O]4

vernal equinox

p. 0]4

winter solstke

p.034

Earth', Tilted Axi, Although you can', feel it, Earth is moving at close to 1.600 km (1,000 mi) per hou r. Thai is

because Ea rth is spinning, or rotating, around an

READING SKILL

imaginary line called an axis. Pi<:;lure Earth's axis

(/Il1se and Effect Complete

as a line that goes from the North Pole through

the charI to show some 01

the cen ter of Earth to the South Pole. In relation

the effe
to Earth's orbit around the Sun, the axis is nol vertica l, or s traight up and down. It is titled at an angle of 23to. It ta kes 23 hours and 56 minutes-one day- 'o< Earth to ma ke one fu ll rotation on its axis. As Ear th rotates, different parts face the Sun. It is daytime on the side of Earth facing the Sun. [t is nighttime on the side facing away from the Sun.

Earth's tilted aKis is why Eart h has seasons. T

As Earth spins on ils axis, it also mo\'cs around the Sun. One fullirip around the Sun is called a revolution. Earlh takcs 365 t days, or one year, to com plete one revolution. The path of E.1rth's revolution is called its orbit. The orbit is a kind of oval shape called an ellipse. Because of Earlh's tilted axis, different pariS of Earth lilt toward or away from the Sun during its Irip around the sun. This tilt causes seasons. In the photograph on page D32, E.1rth's northern half is tilted toward the Sun. In this position, it is summer in the Norlhern Hemisphere and winler in the Southern Hemisphere. In the pholo below, six months have passed. Earth is at the opposite cn~t uf ttl; urbit. Now EMth's :;outhcrn h
Why does a tililoward Ihe Sun bring warmer weather? 1nere

Why do the No.them and Southern hemispheres have opposite

uason$1

Solstices and Equinoxes On June 21 or 22, the North Pole of Earth's axis til ts toward the Sun. This event marks the summer solstice and the beginning of summer in the Northern Hemisphere. On this longest day of the year, the hemisphere receives more sunlight than on any other day of the year. Six months later, on De<;ember 21, or 22, the North Pole poin ts dire
called equinoxes. Periods of dayligh t and dark ness are each 12 hours long every place on Earth. One of those events occurs on March 20 or 21. This marks the vernal equinox, which is the first day of spring in the Northern Hemispherc. The second of these even ts occurs six months later, on September 22 or 23. This even t marks the autumnal equinox, which is the first d ay of fall in the Northern Hemispherc. ~ UtlSEJ.NDUFHT

How do the lengths of day and night compare during a solstice? During an equinoK?

.,., 1--

••,• ~ E

.~

~ ·10' ( ·20' (

·10' (

....

Apfil

Month

The angle at which the Sun's

'"

' ')'$ strike an area affe
Seasons In everyday life, seasons lire periodS of a particular kind of weather. Earth scientists, however, define seasons by the position of Earth in its orbi t. By this definition, al! places on EMth hlwe four seasons: spring, summer, fall , and win ter. Yet the effects of these seasons are extreme in some places, while they hard ly exist in others. NeM the equator, the Sun's rays arrive at almost right angles. This causes the Sun's energy to be more concentrated. Near the poles, the rays arrive at much sharpe!" angles. This causes the same amount of sunligh t to be spR'ad out. This difference affects a\'era ge tempera tures. Look at the graph aoo\'e.

Places close 10 the p<>]cs, s uch as

McMurdo in Antarctica, have cold weather all year long. Compare its temperatures to those of Panama City, which is ncar the equa tor. Other places have wide variations in temperature throughout the yea r. Compare the tcmper1ltures of Chicago, Illinois, and S,mtiago, Chile, These ci ties are both about halfwily between thc equator lind a pole, but are on opposite hemispheres. How do their yearly temperatures compare? A place's position on Earth is the most import,mt factor ilffccting its temperature and seasonal changes. As you have read in other chapte rs, olher faclors ilffe<:t climate as welL Why do places near lhe equalor Ilave Il iglltr yeaN ound temptratures Illan ptacH near me polts?

Height of Sun ~bo ~~ HOrIZon r

padlin "

•

paoth in winter

East

...,

Earth's Hori. on

S(ientists can predict the exact positions of the Sun in the sky, Why does the Sun rise higher in summer than in winter?

Ideas About the Sun Hundreds of years ago, people believed many false ideas about Earth and Sun. As they looked up at the sky, they thought that Earth was the center of the universe. The Sun and other objects appeared to revoh'e around it. In the 1600s, Italian astronomer Galilee published a book about the universe called Dialogue. The book presented evidence that the Sun la y in the center, while Earth and other planets revolved around it. Galileo was arrested for promoting this idea! Today, he is recognized for his courage and for being COITI'CI. Ha\'ing built on the work of Galilee and others, scientists now can predict the positions of Earth, the Sun, and other objects in space. 036 ' Chapler 10 ' Lesson 1

Another false idea is that seasons come from Earth's chan gi ng distance from the Sun. In fact, Earth's elliptical orbit brings it slightly closer to the Sun in December than in June, However, the effects of the changing distance are \'ery minor. ,\ S you have read, seasons result from Earth's tilted axis and revolution around the Sun. The tilt causes the Sun to rise higher in the sky and makes the days last longer during the summer. The illustration shows how the Sun appears to tra\'el across the sky in the Northern Hemisphere. Its higher path in the summer provides more daylight and warmer temperatures. ~ ('liSE 'NO lFFEtT

Describe some falSI! ideas people held about Earth.

Review

o MAIN IDEA What calJSes day

and night? What talJSes seasons?

o VOCABULARY Compare a

Eafth rotates on iu alis
solstice with an equinox. What seasons do these I'Vt'fIts man:?

o READING SKILl: Cause and Effect Chicago, tllinois.lies midway between the North Pole and the equator. Why does Chicago have a wide range 01 yearty temperatllles?

Earth's nls is slightly tilted. This UOUSft parts of ElII'ttI to point tow.,11 or lWIay 'rom the Sun during its orbit. The rt'Slllt is 'our SUSOllS; spring. su mmer, lall, and winter. The (onuntration and amount 01 sunlight • region rt<eivt'S determines the (~r,'l(teristics 01 its

seas.ons.

o CRITICAL THINKING: Apply Explain why ~ummer in the Northern Hl.'IIlisphere occurs when winter occurs in the Southern Hemisphere.

o INQUIRY SKill: Use Models How would you create a three· dimensional model to explain Earth's cycle 01 seasons?

.eTEST PREP During an equinox. the number of hours 01 daylight is A. greater Ih
hours 01 dan:roess. B.

MATH Make a tine Graph Research local

temperatures owr the last four ween. Cakulate the average high temperature and the ilVerage low temperature lor ea<:h week, Then create a line graph similar to the one on page 035,

C. the same as the oomber of hour~ 01darkness.

O. sometimes less than and sometimes greater than the flUmber of txx.~ 01 darkness.

TECHNOLOGY Wri te a Report Hundreds of years ago. asllOl'oOlflelS studied the skies with astrolabes, sextants, and other tools. Research tools such as tllese and how they were used, Write a reporlto show your findings.

than the oomber of hours of daOOlt$$. les~

, ~ Technology •

Viiit www.edupI.Ke.rom/lcpl to rond CIOJt ~about EMIl's motion.

Primary Source As the summef solstice ilppken ?

SOCIAL STUDIES

1 READING (HE(k Wha t is the Arctic Circle?

2. WRITE ABOUT IT Why does Alaska have such extreme lengths of day and night?

3. TAU( ABOUT IT How do you think Alaskans cope with long summer days and long winter nights?

Why Does the Moon Have Phases? Why It Matters ...

• •

PREPARE TO INVESTIGATE

Do you look at t ile Moon? : Inquiry Skill Would yo u like to visit it, as some Compare When you compa re astronauts have done? The Moon has •• fascinated observe rs for tho usands

objects or events, note both • similarities and differences. • • Materials • • small loam ball •

of years. Many civilizations built calendars around the Moon's phases. How do you think laday's calendar reflects the Moon? • • fi ashlight

Sdence and Math Toolbox For step 1, review Using a Tape Measure or Ruler on page H6.

It's Just a Phase! Procedure Safety: Do not shine the flashlight directly at someone's eyes.

o

Collaborate Dim the lights in the room. Hold the small ball slightly above your head, as shown in the photo. Have your partner hold a flashlight about a meter (3 feet) away. Shine the flashlight on the ball.

G

Use Models Your head represents Earth, the ball is the Moon, and the flashlight is the Sun. Observe how the Moon appears to you in this position.

e

Observe As you hold the Moon steady,

o

Communicate In your Science Notebook,

slowly rotate in a circle. Your partner should not move the flashlight. Observe how the Moon appears to change.

draw how the Moon appeared in at least four different positions. Organize your

drawings to best show the process they model.

"

Experiment Switch roles with your partner and repeat the procedure.

Conclusion 1. Compare

Describe what the Moon looked like at each of the four positions.

2.

Analyze Data Using your data, explain why you think the Moon appears to change shape from night to night,

Design an Experiment How does Earth appear when viewed from the Moon? Does Earth appear to change shape, or does it alwa~ look the same? Design an experiment to find out.

\.eat~ by Reading VOCABULARY lunar e
solar eclipse

....."" ",.

REAOING SKIll S~q"eftce Ike a graphic organizE'! such as the ont shown 10 lJar;k the sequence 01 the phases of the moon.

DOD

Earth's MAIN IDEA The Moon reV(llvu a.ound Earth, and

together they revolve around the Sun , The same side of the Moon always laces Earth, but the Sun lights di fferent parts of it at diffe, enl limes.

The Moon Earth has one n....'tural salE'liite, an object that rcvoh'cs around ilthrough space. This sMellile is the Moon. The Moon is a sphere th at is about one-fourth thc size of Ea rth. The Moon's surface is rocky and includes large and small craters, or holes,

From Earth, large craters appear as da rk areas on the Moon.

The Moon's mass is about 80 limes lighter than the mass of Earth. Because of its smaller 1Th1SS, the Moon's surface gravity is about one-sixth of Earth's gravitational pull. lis weak gravi ty prcvents the Moon from hal'ing much of an ntmospherc. However, its pull of grn"i t)' is strong enough to affect tides on EMth.

Viewing the Moon If you've ever gazed at the Moon, you know that it appears to be the biggest and brigh test object in the night sky. The Moon appears so la rge be<:ause it is very close to E.1rth. However, the Moon is actually smaller than other objects in the sky. For instance, the planet Venus appears as a dot in the sky, only a little larger than a star. Yet it is about the same size as Earth! Because the Moon is closer, it appears bigger. Although the Moon can look very brigh t, it does not produce any ligh t. Instead, sunlight reflects off the Moon's su rface. This is why you can see the Moon from Earth. U ke Earth, the Moon rota tes on an imaginary axis. Also li ke Earth, the Moon revolves. While Earth revolves around th(' Sun, the Moon revolves around Earth. The Moon takes 27 ~ days to com plete one revolution around E.1rth. Some time in the dis tan t past, the gravitational pull of E.1rth affccted the Moon's period of rotation. Now the Moon's rotation ta kes the same amoun t of time as its revolution around Earth. So, the same side of the Moon always faces Earth.

~1'Hlm!(.

Why t~n you ~cc the Moon

Radius: 1,731 km

Oistancc from Earth: 384,400 km to 405, 500 km

Pcriod of Rotation:

HI Earth days Surface: na tcB, ridges, and plains covered with a fine dust

Surface gravity: about ~ Earth's graYi tational pull

Temperature: range ' .om - 2n' ( to 123' (

Period of Revolution:

Hi days Atmosphere: very, very thin layer of mostly hydrogen and helium

from Earth1

Most of the rocks on the surface of the Moon formed about 4.6 billion years ago when lava tooled and hardened . ...

D43

Phases of the Moon The Sun always lights one half of the Moon. As the Moon orbits Earth, different amounts of the lighted half are visible from Earth. The shapes created by the changing amounts of the visible lighted areas are called Moon phases. A comple te cycle of Moon phases takes about one month. The first phase in the cycle is the new Moon. Find the n('w Moon in the photos to the right. During this phase, the Moon is bt>tween Earth and the Sun. Because its lighted side is facing away from Earth, the Moon ilppears dilrk when viewed from Earth. As the Moon continues in its orbit, more of the ligh ted area becomes visible. During this time, the Moon is described as waxing, or growing. The waxing crescent phase appears after th(' new Moon phase. L..'1tcr, when half of the Moon's ligh ted area is visible, the Moon is in its fi rst quarter phase. The portion of the lighted area continues to grow until the full Moon phase is reached. During this phase, the entire ligh ted side of the Moon is visible from Earth. At this poin t, ll,,, Eilrll, i" loct"' ..""" the Moo" ""oJ the Sun. After the full Moon phase, the area of the ligh ted side that is visible from Earth bt>gins to get smillier. The Moon is said to bt> waning. Phases during this half of the Moon's revolution include wilning gibbous, Iilst quarter, and waning crescent. The visible lighted area continues to decrease in size as the Moon finishes its revolu tion ilround E..'1rth. It takes about 29 days for a compkte cycle of th(' philses of the Moon - from one new Moon to the next. Look agilin at the circle of photographs. Remember that these appa rent changes in shape depend on the Moon's position in space relative to E..'1rth ilnd the Sun. Now look at the drawings in the inner circle. They show what the Moon looks like to an observer above the system in spilce. All of the drilwings arc illike because the side of the Moon facing the sun is always ligh ted. [t is only the area visible from Earth thil t seems to change shilpe. Why does the Moon go through pha ses?

Types of Eclipses

Eclipses ouur when Earth, the Sun, and the Moon form a straight line in space . ..

Eclipses An eclipse occurs when one object pilSses into the shildow of il nother object. When Eilrth, the Sun, and the Moon form il strilightline, two kind s of eclipses can occur. A solar eclipse occurs when the Moon passes between the Sun and Earth. The Moon casts a shadow on Earth's surfilce. The darker ilrea of the shadow is called the Umbril. The li ghter area is the penumbra. The pa rt of Ea rth's surface within the umbra experiences a total solar eclipse, as shown in the photograph il t the top right. The part of Earth's surface in the penumbra experiences a partial solar eclipse.

046 • Chapter 10 • l esson 2

A lunar edipse takes place when Earth passes dire
S(QU~M((

Compare the positions of Earth, the Sun, and the Moon during a solar eclipse and during a tunar eclipse.

Review Visual Summary The Moon is E,trth's only natura l s.atellitt,

o MAIN IDEA Why is the same

side of the Moon always visible from Earth?

a VOCABULARY hplain what is meant by Moon phases.

9 Tht s.ame s ide of the Moon is al ways seen Irom Earth. The Moon appea rs to change sha pe as it revolves around Ea rth. During a solar ecli pse, the Moon passes directly be tween Earth and th e Sun. During a lunar eclipse, Earth passes directly betWH n the Moon and th e Sun.

READING SKilL: Sequence List the se-quenct of the phases of the Moon starting with waxing gibbous and ending with the first quarter.

o CRITICAL THINKING: Apply How would you determine whal the phase of the Moon will be 10 da~ from today?

o INQUIRY SKILL: Compare

Compare a solar eclipse with a lunar eclipse.

.,tTEST PREP Whal happens during a lotal solar eclipse? A, The Moon blocks oot all of the Sun. S. The Sun blocks out all of the

MATH

Applya Formula The radius (r) of Earth's Moon is 1,737 km and the diameter (d) is two times the radius (d = 2r). Use the equation C '" ..dto determine the Moon's circumference (C).

WRITING

Narratiye How has the Moon influenced you? Do you notice its phases? Would you like to visit the Moon? Discuss the Moon in a story or poem.

M~ .

C. The Moon blocks 001part of the Sun. D. The Sun blocks oul part of the M~

~ Technology

. . Vi~l w_.eduplace.comlscpllo firK! 001 more about Earth's Moon.

Everything about the Moon is extreme. Because the Moon hal no atmosphere to even out the Sun's radiant ene rgy, temperatures vary from blistering hot to frigid cold. The surface Is pockmarke d by micrometeorites, which bombard like tiny bullets from space. Dangerous radiation fries everything. It's about as unfriendly a place for life al you could imagine. Nevertheless, over the course of thr_ years in the 20th century, life was there-human life. The Apollo missions to the Moon were among the greatest scientific achievements In history. Six separate times astronauts landed on the Moon, where they walked, hopped, and even drove around, gathering samples and doing experiments. Talk about extreme sciencel

READING

: Compare and Contrast

The only thing ~tandjng

bet ..... een the

astronauts and death was their remarkable space suilS. The suits supplied air, kept

them (001, ilnd protected them from radiation and micrometeorites.

'"

Vocabulary Complete ea( h senten(e wi th a term from the list. You may use each term more than once. 1. A(n) _ is an imaginary line about wI1ictI a bOOt rotates. 2. During lilt _ the Sun.

the North Pole is at its greatest tih awa'j from

3. During a(n) _

Earth passes directtv bttween the Mooo and the SI..rt.

are called _ _

Dis 032 lunar eclipse D46 Moon ph.Hes D44

4. AppafMt changes in the shapes of the Moon throughout the month 5. _

autumnal equino. D34

occurs, spring begins in the Northern Hemisphel"e.

revoMion 0)) solar edipse D46 summer solstice 034 vemal equino. 034 winter solstice 0)4

6. The North Pole is tilted directly toward the Sun during the __ 1. 'NIlM the Moon passes dirKtly between the Sun and Eilrth, iI(n)

_ _ occurs. 8. The first day 011.111 in the Northem Hemi5phere marks the _ 9. During a total _

the Sun IS In the umbra 01 the Moon's shadow.

10. The palh 01 Earth's _

I

.

is elliptical.

Test Prep

Write the letter of th e best answer choice. 11 . During a solstice, _ fl . Day and night are the same lerJgth during A. one 01 £arth·s ~ is tiklld tow.wd tilt S!.w'1 B. neither poll' is tikfd towa«ltllt Sun C. ~ng begins in tht Northern Htmisphere O. Iail begins in tht Northern H~

12. Places oeilr the equatOf tend 10 bt warm year·round because _ A. 01 §OIar « Iipses B. 01 ...... « Iipses C. tht s..·s rays SINe this P¥t 01 Earth dirI'CtIy D. the Sun's rays are slantfd om this pall 01 ,.",

050 •

~~~:f 10

(h~ pter

A.

wintl!f

solstice

B. a tOLlI solar I'dipse C. vernal equinox O. iI tOLlI b\ilI «!ipse

14. The same side 01 the Moon is illw~ visible Irom Eilrth be
____________~.~'~imo~M~~~'~~"~':"~______~

Inquiry Skills 15. Cause and Effect How does Eanh's tilt on its axis cause sea50flS to change in different pans 01 the W
17. Analyze Explain why the Nonhern and Southern Hemispheres have opposite seasoll5 at the same time.

16. Sequence Identify the Moon phase shown below and explain how it will change over the next two weeks. Ill(lude drawings in your answer.

18. Synthesize Exp la in why the shonet day of the ~ar in the Northern Hemisphere is ()(I December 21 or 22. Where is this the longest day? 19. haluate look agilin at the iIIustrati011 and photos on p<>QeS 045 and 046. What type 01 eclipse occurs when the Moon is in its full Moon phase? In its new Moon phase? Expla in.

20. Hypothesize Why 00 you thin k lew people have witnessed a total solar eclipse while many people have observed lunar eclipses?

Performance Assessment Observe the Moon Observe and draw the Moon on five or six «l(l:;e(utive nights. Identify the phases you observe and predi
Map the Concept The chan shows three pairS of scieflCe terms. Complete the chan to explain how they differ.

Solstice

Equinox

"'.

Moon

full Moon

Solar edipse

Lunar

e
LESSON

1

Is a "shooting star" really a star? Read about it in lesson 1.

Is this a six-wheeled skateboard or a tool to explore other planets? Read about it in lesson 2.

LUSON

3

What forms from a

nebula, like the Crab Nebula shown here? Read about it in lesson 3.

D53

What Orbits the Sun? Why It Matters...

PREPARE TO INVEST1GATE

Earth is only one small part of the solar system. The Sun, eight other planets, and thousands of smaller bodies belong to this system, too. Yet only Earth is able to support life, at least as far as scientists can tell. Understanding Earth's position in the solar system is one key to

Inquiry Skill

understanding why it supports life.

Research When you rl'sear(h, you use library reference

materials, sl'arch the Inlernet, and talk to I'xperts to learn science information.

Materials • I,"ye in~~ l~rd • metric rule.• 2 gummed rein forced rings • 2 bfass faslffiers • string (30 em long)

Science and Math Toolbox For step 1, review Measurements

on page H16.

A Very Long Trip! Procedure

o e e

e e

Measure Use a ruler to find the midpoint of the short side of a large index card. Draw a straight line across the center of the card. Measure Mark two points, each 2 em in from the edge of the card. Then measure 2 em in from one of the points and draw a small circle. l abel the circle NSun.N

Use Models Attach reinforced rings over the two marked points on the card. Carefully push the brass fasteners through the rings and the «Ird. Spread the prongs of each fastener. Tie the ends of the string t o form a ci rcle with a circumference of about 25 em. Loop

the string around the brass fasteners. Collaborate Have a partner hold the edges of the card while you insert the tip of a pencil inside the string loop. Keeping the string tight. draw an ellipse by moving the pencil around the inside of the string. The ellipse models the orbit of a comet.

Conclusion 1.

Observe How does the orbit of a comet compare with the orbits of the planets?

2.

Predict What do you think happens to a comet when it reaches the point in its orbit closest to the Sun?

Research find out more about comets by researching at the library or on the Intemet. Use your findings to make a poster.

\.eat~ by Readi.g VOCABULARY asteroid

comet meteor meteorite meteoroid

planet sol ... system

.

"" p,OS9

",'"

,,,,,, "". ,,,,

."",

READING SKILL

Text Structure Use a diagram like the one below

10 record details about the partS 01 the solar system.

o

The Solar System MAIN IDEA The Sun and the bodies that revolve around

il

m~ke

up the so la. syste m. The sol,,, system Is a small

part of a much larger system calied th e Milky Way ga laxy.

The Sun and Its Neighbors In your neighborhood, you r neighbors are the people who lin! nea r you. Earth's neighborhood is the solar system. The solar system is the Sun and all bodies that travel, o r revol\'c, around it. Earth is onc of ninc planets, large bodies th at revolve around the Sun. The planets do not make their own light, bu t shine by reflecting the Sun's light. The Sun is by {;IT the largest and most massive part of the solar system. Its gr.H'ity holds the other parts in thcir positions. Many planets, including Earth, have one or more moons. Smaller members of the solar system include asteroids, comets, and meteoroids.

En'n with its thousands of parts, the solar system is a very small part of a much larger system called the Milky \,/.\y galaxy. You'lIleam more about galaxies in Lesson 3. Scientists believe that the solar system is about 4.6 billion years old. It formed from a hot, spinning cloud of gases and dust. Over time, gravity pulled the gas and dust toward the center of the cloud. causing the cloud to collapse. As it continued to spin, the cloud flattened and its temperature rose. Eventually, great heat and pn:-ssure built up ncar the «'nter of the cloud. Nuclear reactions produced a star now cdlled the Sun. Away from the center of the spinning cloud, temperatures were cooler. Matter in this cooler part of th~ cloud ~g" n to come together to form the planets and their moons.

Planets closest to the Sun formed from heavy, rocky material. Farther from the Sun, planets were able to hold onto lighter gases and form much larger planets. Moons eventually formed around all but two of the planets. Along with the planets and their moons, other small bodies formed in the solar system. These include asteroids, comets, and meteoroids. The paths, or orbits, of all of the bodies that tra\'el around the Sun are shaped like slightly flattened circles called ellipses. The strong gravitational force of the Sun holds all the objects in the soldr system in their orbits.

@ ml'i!llihll What does the illus tration show about the ptan@ts in the solar system1

Moons are nat ural sa tellites that ol bit a planet.

10 ;s OM of thfo moo"" of Jupi ter. M;tny wolcan06 dot its suriace.

S"o,nn's moon EMel.d1tS has an icy suriace of smoo th plains. (fa ters. and loog (racks and ridge-s.

The vaUf)'S of Aflel. I moon of Uranus, may have formed during violent moonq\lake$.

Moons

Asteroids

[n Chapter 10, you leamed about Ea rth's moon- the s.1tellite that is o ften called the Moon. Did you know tha t ~stronomers have discovered about 140 other moons in the solar system? All these moons ~re held in their orbits by the gravitational attraction of their planets. Unl ike Earth's Moon, some moons ha ve atmospheres surrounding them. Others show evidence that water or ice may lie deep beneath their surfaces. One moon has acti ve volcanoes, and an other has geysers!

An .. steroid is a relath'ely Sm..1n, rocky object tha t orbits Ihe Sun. Scientists estimate tha i millions of these ch unks of rock and metal exist in the solar system. Most of them orb it in a band called the asteroid belt, located between the orbits of Mars and Jupi ter. Asteroids range in size from hundreds of kilometers in diameter to only a few meters across. Many asteroids have very peculiar shapes. Some even look like baked potiltoeS! One theory about the ori gin of the asteroid s is that Jupiter 's strong pull of gravity prC\'ented them from coming together to form a planet. Anotner, less likely idea is tha t the asteroids are remnants of sc\'eral planets that collided and broke apart . .. Asteroids are small, rocky bodies tlla! orbit the Sun, many in a belt between Mars and Jupiter.

Comets A comet is a small, orbiting body made of dust, ice, and frozen gases. The solid center of a cornel is its nucleus. Like all objects in the solar system, comets orbit the Sun. However, most comets travel in very long, elliptical paths similar to the one shown on this page. When a cornet approaches the Sun, frozen solids in its nucleus vaporize. Gases and dust are released, producing a glowi ng ~ion called a coma. Energy from the Sun causes the coma to grow. Charged particles streaming from the Sun push particles out of the coma, producing a glowing tail that ca n T('ach millions of kilometers into space, The orbits of some comets extend to just beyond the planet Neptune. These comets make one complete trip around the Sun in fewer than 200 years. They arc called short-period comets. The best known comet, Halley's comet, is iI short-period cornel thilt orbits the sun about once

e\'ery 76 years,lt will next be visible from E.lrth in the year 2061. The orbits of other comets extend much farther from the Sun. Some scientists belie\'e that most of these comets ilre found beyond 1'1uto. As many as a trillion comets mily exist in this region. These comets can take up to 30 million years to orbil the Sun! They arc called long-period cornets. Hale-Bapp, a long-period comet identified in 1995, takes nea rly 2,500 years to orbit the Sun. 'Nhat causes the - t ail" of a comet to form ?

Named for its discoverer, Yu]i Hya~utah, this come t was one of the brightut to appro.och the Sun in the 20th c.n tury. •

Meteors Have you ever seen a "shooting star" sweep across the night sky? It produces bright, short-lived streak of lighl. But such streaks are not moving stars al all. They are meteors. A meteor is a streak of light caused by a chunk of malter that enters Earth's atmosphere and is heated by friclion with the ai r. These chu nks of matter are called meteoroids. For a few moments, the meteoroids burn as they fall, appearing as streaks of light against Ihe night sky. A ~, meteoroids are the size of asteroids. But most OIl"\' much smaller. Many are smaller than a grain of sand. Sometimes Jll(lre meteors are visible in the sky than usual. These >howe'$ c..:(W when Earth passes through particles that were shed from the tails of comets. ..

Meteor

events are called meteor showers. During the meteor shower shown in the photo below, an average of 50 meteors per hour could be SC('n. Meteor showers can last from a few hours to a few days. Most showers occur when Earth passes through clouds of dust left orbiting the Sun by a passing comet. Sometimes, the falling rocks slay intact during their trip through Earth's atmosphere. When these Objects strike the ground, they are called meteorites. Most meteorites are believed to come from the asteroid belt. When large meteorites strike Earth's surface, they form bowlshaped depressions called impact craters. The impact crater shown below is the Barringer Crater in Ari7.ona. It formed sometime between 20,000 and 50,000 years ago. How is a meteorite different f rom a me teor?

The Barringer impact crater Is over 1 km wide and almost 200 m deep. T"._ _ _ _ _ _. .

•

Review

o MAIN tOEA What different Tht solllr Iyslem consisls of I~ Sun, nln ~ plan~ls, I~ir

moons. ,00 lIIlIny Ol~r srnaJI~r bodif'S th'l revolve ~round the Sun. All bU I two planets in Ihe solar system h~ve lit iust one moon. Moons. comels, lind aSleroids are ~mong tilt small,," bodif'S in Ihe solar sys tem , Mel~roids

lire bits of

maner thai bur" up when t~ enter £.nh',

a tlllOsp'Wf.

types of bodies make up the solar system?

o VOCABULARY Write a sentence using the words asteroid and

camet.

o READING SKilL.: Text Structure Make a brief outlif'le tllat shows how tllese terms afe related: plilfII'ts. moons. asteroids, thf! Sun.

o CRITICALTHINKING: Apply

Earth and its Moon formed at about the same time and from the same PI"O(1'SSI'S. Why do you think Earth's surface has fewtr crattrs than the surface of the

-,

" INQUIRY SKILLS: Research How coold you find oot lllOfe about (ollecting meteorites?

~TEST PREP MATH Calculate Circumference The aVerage radius of Eartll's orbit around tile Sun is approximately ISO rnill iOfi km (93 million mi). Using tile formula ( - l"O"t calculate tile circumference (C) of Earth's orbit. Suppose Eartll's orbit to be circular for this calculation.

ART Mak@a PostH learn more about OIle of tile moons of Jupiter, Saturn, Neptuf'le, or Uranus. Make a (olor drawing of till' moon, labeling its interesting features. Include a paragrapll describing the moon and what makes it uniQlIf.

Small ' ocky objects that orbit the Sun belWf'en Mars and Jupittr a.e called A. meteofS.. B. meteorites. C. comets. D. asteroids. ~ Technology ... VISit www.fl!uplKe.comlscpllOfind OUI more about the solar $)'Stem.

What Are the Planets ? Why It Matters ... By studying other planets and their moons, scientists have learned a lot about Earth and its Moon. Studying the solar system also provides dues about t ile stars and galaxies that lie beyond it.

PREPARE TO INVESTIGATE

Inquiry Skill Use Models Some models

are scale models. All parts of a scale model are larger or smaller than Ihe Sill" of the actual object being modeled,

but afe in ellact proporti ons.

Materials • • • • •

marker metric tape measure piece of string (40 m) 10 wooden stak~ (lO em long) masking tape

. 10 cardboard rectangles • modeling day

S!ience and Math Toolbox For step 1, review Using a Tape Measure or Rul er on page H6.

Scaling the Solar System Procedure

41 Measure Work wit h t hree other students, Obtain the scale d istance values from your teacher and write them in your Science Notebook. Using the marker and the measuring tape, mCirk off along the string

o

the positions of the Sun and planets. Use Models label one of the rectangles

as the Sun. Tape t he sign to a stake. Gently push the stake into the ground, if

out doors. If you are indoors, make a small

e

clay ball and push the stake into the day. Collaborate Work with the members in your team t o label th e rest of the

rectangles with t he planet names and tape each to a stake.

G

Use Numbers Have one team member hold

the end of the string that represents the Sun while another student stretches the string so that it is taut. The other students in your team should place the planet stakes in thei r correct positions along the stretched string.

Conclusion 1. 2.

Analyze Data Which grou p of planets-the inner planets or the outer planets-is doser together?

Use Numbers Study t he distances between the first four planets from the Sun. Is there a pattern? If so, what is the pattern7 Then describe distances among the outer planets.

•

Investigate More! Design an Experiment Find the d i amete~ of the plar.ets on pages D6s-066.

Use these diametefs to make a -;cale-size model of the Sun <md each of the nir'H! plar.ets. Use a -;cale of I em to 1.000 kin.

vat" by Reading VOCABULARY jnner planets

outer planets READING SKILL

",. ""

Compare and Contrast

U$t' a diagram like the one below to compa.e and contrast the inner and outer plafll'ts.

The Planets MAIN IDEA There are nine planets in our solar system.

The four planets doses! to the Sun are <;ailed the inner planets. Tl>e remaining five ilre called the outer planets.

The Inner Planets The first four planets from the Sun aTe Mercury,

Venus, Earth, and Mars. These planets are called the inner planets because they Me closer to the Sun

than the othe r planets in the solar system. The inner pin nets have ceTtilin characteristics in common. They are roc ky and much smaller than most of the other planets. Yet, if you could travel to the inner planets, you would find them very different from E.1.rth and from each other. Mercury is the smallest of the inner pIn nets and the one dosest to the Sun. Mercury's surface temperature vnries widely between its day and its night. During the planet'S slow rota tion, the side facing the Sun becomes extremely hot, while the side fac ing away becomes extremely cold.

Mercury Mercury's surface has many craters, Some of these may contain frozen water. T

•

Venus .. Venus lias a few craters on its surface. A thick, poisonous atmosphele sUllounds i planet.

The surface of Venus, the sc